let's see....frogspawn, colt, mushrooms, plate coral, porites, xenia, star polyps, gorgonian, montis.
sadly I lost my butterfly in an ich outbreak a few months ago and I'm still bummed. He was a great fish. I can also confirm that he ate baby aiptasias. for a long time I've had one big aiptasia in the back that I can't reach to kill it. While the butterfly was with me that was the only aiptasia in the tank. Now that he's gone, small ones are cropping up again like they used to.
I do think a 4' tank is too small though. I wouldn't put one in a tank smaller than 6'.