How Do These Creepy Eyeball Rocks Form?

SciShow is supported by Brilliant.org. Go to https://Brilliant.org/SciShow to get 20% off of an annual Premium subscription. Rocks or mineral crystals can often remind us of other things in our daily lives, but coming across some of THESE rocks might be one of the creepiest experiences a rockhound can have!Hosted by: Hank GreenSciShow is on TikTok! Check us out at https://www.tiktok.com/@scishow ----------Support SciShow by becoming a patron on Patreon: https://www.patreon.com/scishow----------Huge thanks go to the following Patreon supporters for helping us keep SciShow free for everyone forever:Bryan Cloer, Chris Peters, Matt Curls, Kevin Bealer, Jeffrey Mckishen, Jacob, Christopher R Boucher, Nazara, charles george, Christoph Schwanke, Ash, Silas Emrys, Eric Jensen, Adam Brainard, Piya Shedden, Alex Hackman, James Knight, GrowingViolet, Sam Lutfi, Alisa Sherbow, Jason A Saslow, Dr. Melvin Sanicas, Melida Williams, Tom Mosner----------Looking for SciShow elsewhere on the internet?SciShow Tangents Podcast: http://www.scishowtangents.orgFacebook: http://www.facebook.com/scishowTwitter: http://www.twitter.com/scishowInstagram: http://instagram.com/thescishow----------Sources:https://spookygeology.com/eye-agate-the-rock-that-looks-back-at-you/ https://ieeexplore.ieee.org/abstract/document/6213238 https://gem-a.com/gem-hub/gem-knowledge/optical-chatoyancy-cats-eye-gemstones-sillimanite https://www.sciencedirect.com/topics/earth-and-planetary-sciences/vesicle https://www.sciencedirect.com/science/article/abs/pii/S0009281912000670 https://www.mdpi.com/2075-163X/10/11/1037 Images:https://commons.wikimedia.org/wiki/File:Agate-Quartz-49959.jpghttps://commons.wikimedia.org/wiki/File:Desert_flower.jpghttps://commons.wikimedia.org/wiki/File:Cymophane.jpghttps://commons.wikimedia.org/wiki/File:Eyeballed_by_all_the_eye_agates_(27395607964).jpghttps://commons.wikimedia.org/wiki/File:Agate-_%26_quartz-lined_geode_5_(32375570960).jpghttps://commons.wikimedia.org/wiki/File:Agate_nodule_(%22Lake_Superior_Agate%22)_(Jo_Daviess_County,_Illinois,_USA)_14_(34743267776).jpghttps://www.istockphoto.com/photo/waves-in-light-agate-structure-gm509407138-85755831https://www.flickr.com/photos/jsjgeology/16128028613