["Umm, fish?"]

Thanks, Brian! But not "has" reproduced, "can" reproduce. I was just making a silly, flippant comment about animals and their sex lives. Sorry!

lion-clown--I do have fish and I guess that's a possibility. I have two anthias, but whatever it is looks too large to have come from them to me. And the Bangaii is still holding his eggs. Anyway, I don't believe that eggs have cilia like that. I think it's more likely to be a coral planula from a brooding coral or some ciliated organism along for the ride eating sperm. If that's a sexual by-product at all.