Ok, so I could not resist this guy being sold at BTA price with 20% off all saltwater critters, so 24 bucks. I'm pretty sure about what it s but I want the experts to weigh in. Tips of tentacles are a glowing green/yellow. Mouth is tight, it's been roaming around my tank staying on the rocks, pretty actively figuring out where it wants to settle. Husband saw it when he got up at 5 AM this morning fully opened up (mouth tight) and estimates it at about 5 inches across. Picture is from when it was still at Petco.