Found 3 on a zoo rock, the big one was stinging about 5 or 6 zoos.
Googled it since I'm cheap and didn't want to buy anything from an LFS.
Get a syringe with a tiny needle, and some lemon juice. Stab that sucker in the head and shoot it up. Hardest part is getting the needle in there while the aiptasia is open! All mine were holed up, and when they closed you couldn't find them. Actually, the hardest part was getting a needle. Pharmacies can only give them to people who use insulin, otherwise they just assume you're Kurt Cobain.
Next day the zoos were opened up real big!