pincushion

Anyone know ? https://www.facebook.com/photo.php?v=10201160421887107&set=vb.1666771429&type=2&theater

I'm relatively new to the hobby and saw an orange pincushion urchin at my LFS. they called it a "Halloweeen pincushion". I was wondering if it will eat coralline? I wanted to get him but I love my coralline algae

so 2 days ago i cleaned my tank did a water change and got rid of most of the green that had taken over. i found my cowrie dead in my filter (which isnt a bad thing but still sad) and yesterday my urchin i had for 5 years died. :( so after some water tests and figuring out things were fine...