Unidentified Swimming Object

[antman]

This afternoon I found tons of little things swimming around in my ten gallon reef aquarium. I put it under a microscope and it looks like a tiny jelly fish that slowly pumps around. I have had this aquarium set up for a couple of years and have not made any additions since last summer. I was thinking it was some kind of coral larvae. Maybe apitasia? I have never heard of Apitasia reproducing this way in the aquarium before. I have some mushrooms, tons of star polyps, and some kind of carribean star coral (Blushing Star Coral)in my aquarium. Here is a picture of it that I was able to take, it's a little dark.