Be on the lookout for a handful of exotic rocks inside San Antonio parks this spring.

Rarities include metallic blue and watermelon red stones. Some even resemble popular emojis!

{"author_name":"San Antonio Rocks","author_url":"/groups/177148099377146/","provider_url":"https://www.facebook.com","provider_name":"Facebook","success":true,"height":null,"html":"&#lt;div id=\"fb-root\"&#gt;&#lt;/div&#gt;\n&#lt;script&#gt;(function(d, s, id) {\n var js, fjs = d.getElementsByTagName(s)[0];\n if (d.getElementById(id)) return;\n js = d.createElement(s); js.id = id;\n js.src = \"//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.3\";\n fjs.parentNode.insertBefore(js, fjs);\n}(document, 'script', 'facebook-jssdk'));&#lt;/script&#gt;&#lt;div class=\"fb-post\" data-href=\"https://www.facebook.com/photo.php?fbid=1382821011777192\" data-width=\"552\"&#gt;&#lt;blockquote cite=\"https://www.facebook.com/photo.php?fbid=1382821011777192&set=gm.275530826205539&type=3\" class=\"fb-xfbml-parse-ignore\"&#gt;Posted by &#lt;a href=\"#\" role=\"button\"&#gt;Emily Pippin&#lt;/a&#gt; on &#lt;a href=\"https://www.facebook.com/photo.php?fbid=1382821011777192&set=gm.275530826205539&type=3\"&#gt;Saturday, April 1, 2017&#lt;/a&#gt;&#lt;/blockquote&#gt;&#lt;/div&#gt;","type":"rich","version":"1.0","url":"https://www.facebook.com/photo.php?fbid=1382821011777192","width":552}

{"author_name":"San Antonio Rocks","author_url":"/groups/177148099377146/","provider_url":"https://www.facebook.com","provider_name":"Facebook","success":true,"height":null,"html":"&#lt;div id=\"fb-root\"&#gt;&#lt;/div&#gt;\n&#lt;script&#gt;(function(d, s, id) {\n var js, fjs = d.getElementsByTagName(s)[0];\n if (d.getElementById(id)) return;\n js = d.createElement(s); js.id = id;\n js.src = \"//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.3\";\n fjs.parentNode.insertBefore(js, fjs);\n}(document, 'script', 'facebook-jssdk'));&#lt;/script&#gt;&#lt;div class=\"fb-post\" data-href=\"https://www.facebook.com/photo.php?fbid=10208997317305757\" data-width=\"552\"&#gt;&#lt;blockquote cite=\"https://www.facebook.com/photo.php?fbid=10208997317305757&set=gm.275009942924294&type=3\" class=\"fb-xfbml-parse-ignore\"&#gt;Posted by &#lt;a href=\"https://www.facebook.com/seeitbloom\"&#gt;Tanasha Deacon&#lt;/a&#gt; on &#lt;a href=\"https://www.facebook.com/photo.php?fbid=10208997317305757&set=gm.275009942924294&type=3\"&#gt;Friday, March 31, 2017&#lt;/a&#gt;&#lt;/blockquote&#gt;&#lt;/div&#gt;","type":"rich","version":"1.0","url":"https://www.facebook.com/photo.php?fbid=10208997317305757","width":552}

{"author_name":"San Antonio Rocks","author_url":"/groups/177148099377146/","provider_url":"https://www.facebook.com","provider_name":"Facebook","success":true,"height":null,"html":"&#lt;div id=\"fb-root\"&#gt;&#lt;/div&#gt;\n&#lt;script&#gt;(function(d, s, id) {\n var js, fjs = d.getElementsByTagName(s)[0];\n if (d.getElementById(id)) return;\n js = d.createElement(s); js.id = id;\n js.src = \"//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.3\";\n fjs.parentNode.insertBefore(js, fjs);\n}(document, 'script', 'facebook-jssdk'));&#lt;/script&#gt;&#lt;div class=\"fb-post\" data-href=\"https://www.facebook.com/photo.php?fbid=10154356112286439\" data-width=\"552\"&#gt;&#lt;blockquote cite=\"https://www.facebook.com/photo.php?fbid=10154356112286439&set=gm.262728737485748&type=3\" class=\"fb-xfbml-parse-ignore\"&#gt;&#lt;p&#gt;They're smaller, but won't melt in my hand.\n\n#sanantoniorocks&#lt;/p&#gt;Posted by &#lt;a href=\"#\" role=\"button\"&#gt;Paul Hyde&#lt;/a&#gt; on &#lt;a href=\"https://www.facebook.com/photo.php?fbid=10154356112286439&set=gm.262728737485748&type=3\"&#gt;Friday, March 3, 2017&#lt;/a&#gt;&#lt;/blockquote&#gt;&#lt;/div&#gt;","type":"rich","version":"1.0","url":"https://www.facebook.com/photo.php?fbid=10154356112286439","width":552}

Get ahold of one and you’re onto one of San Antonio’s biggest secrets.

‘San Antonio Rocks’ is a city-wide scavenger hunt the whole family can participate in.

{"author_name":"San Antonio Rocks","author_url":"/groups/177148099377146/","provider_url":"https://www.facebook.com","provider_name":"Facebook","success":true,"height":null,"html":"&#lt;div id=\"fb-root\"&#gt;&#lt;/div&#gt;\n&#lt;script&#gt;(function(d, s, id) {\n var js, fjs = d.getElementsByTagName(s)[0];\n if (d.getElementById(id)) return;\n js = d.createElement(s); js.id = id;\n js.src = \"//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.3\";\n fjs.parentNode.insertBefore(js, fjs);\n}(document, 'script', 'facebook-jssdk'));&#lt;/script&#gt;&#lt;div class=\"fb-post\" data-href=\"https://www.facebook.com/photo.php?fbid=10212035961521756\" data-width=\"552\"&#gt;&#lt;blockquote cite=\"https://www.facebook.com/photo.php?fbid=10212035961521756&set=gm.273715723053716&type=3\" class=\"fb-xfbml-parse-ignore\"&#gt;&#lt;p&#gt;Ready to go hide some rocks!&#lt;/p&#gt;Posted by &#lt;a href=\"#\" role=\"button\"&#gt;Teresa Lain&#lt;/a&#gt; on &#lt;a href=\"https://www.facebook.com/photo.php?fbid=10212035961521756&set=gm.273715723053716&type=3\"&#gt;Tuesday, March 28, 2017&#lt;/a&#gt;&#lt;/blockquote&#gt;&#lt;/div&#gt;","type":"rich","version":"1.0","url":"https://www.facebook.com/photo.php?fbid=10212035961521756","width":552}

Members of the 500-plus strong Facebook group are encouraged to be on the lookout for rocks when they’re at one of the city’s many parks.

When you find one, instructions on the back tell you to re-hide it at a new park or complete a random act of kindness. Some rocks are just for you to collect.

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{"author_name":"San Antonio Rocks","author_url":"/groups/177148099377146/","provider_url":"https://www.facebook.com","provider_name":"Facebook","success":true,"height":null,"html":"&#lt;div id=\"fb-root\"&#gt;&#lt;/div&#gt;\n&#lt;script&#gt;(function(d, s, id) {\n var js, fjs = d.getElementsByTagName(s)[0];\n if (d.getElementById(id)) return;\n js = d.createElement(s); js.id = id;\n js.src = \"//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.3\";\n fjs.parentNode.insertBefore(js, fjs);\n}(document, 'script', 'facebook-jssdk'));&#lt;/script&#gt;&#lt;div class=\"fb-post\" data-href=\"https://www.facebook.com/photo.php?fbid=1485146748165230\" data-width=\"552\"&#gt;&#lt;blockquote cite=\"https://www.facebook.com/photo.php?fbid=1485146748165230&set=gm.275979296160692&type=3\" class=\"fb-xfbml-parse-ignore\"&#gt;Posted by &#lt;a href=\"https://www.facebook.com/alex.huizar.31\"&#gt;Alex Huizar&#lt;/a&#gt; on &#lt;a href=\"https://www.facebook.com/photo.php?fbid=1485146748165230&set=gm.275979296160692&type=3\"&#gt;Sunday, April 2, 2017&#lt;/a&#gt;&#lt;/blockquote&#gt;&#lt;/div&#gt;","type":"rich","version":"1.0","url":"https://www.facebook.com/photo.php?fbid=1485146748165230","width":552}

Don’t forget to post a selfie with your finding using #SanAntonioRocks and inside of the ‘San Antonio Rocks’ Facebook group.

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The group even hosts painting parties to decorate rocks together.

Who knew San Antonio had so many talented artists?

{"author_name":"San Antonio Rocks","author_url":"/groups/177148099377146/","provider_url":"https://www.facebook.com","provider_name":"Facebook","success":true,"height":null,"html":"&#lt;div id=\"fb-root\"&#gt;&#lt;/div&#gt;\n&#lt;script&#gt;(function(d, s, id) {\n var js, fjs = d.getElementsByTagName(s)[0];\n if (d.getElementById(id)) return;\n js = d.createElement(s); js.id = id;\n js.src = \"//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.3\";\n fjs.parentNode.insertBefore(js, fjs);\n}(document, 'script', 'facebook-jssdk'));&#lt;/script&#gt;&#lt;div class=\"fb-post\" data-href=\"https://www.facebook.com/photo.php?fbid=662733793909804\" data-width=\"552\"&#gt;&#lt;blockquote cite=\"https://www.facebook.com/photo.php?fbid=662733793909804&set=gm.274953102929978&type=3\" class=\"fb-xfbml-parse-ignore\"&#gt;&#lt;p&#gt;Easter egg rocks and more....&#lt;/p&#gt;Posted by &#lt;a href=\"#\" role=\"button\"&#gt;Jess Smile&#lt;/a&#gt; on &#lt;a href=\"https://www.facebook.com/photo.php?fbid=662733793909804&set=gm.274953102929978&type=3\"&#gt;Friday, March 31, 2017&#lt;/a&#gt;&#lt;/blockquote&#gt;&#lt;/div&#gt;","type":"rich","version":"1.0","url":"https://www.facebook.com/photo.php?fbid=662733793909804","width":552}

To get in on the fun, join their Facebook group.