What in the world is this

[shookbrad]

I found a tiny (about the size of a pin head) looks like single cell organism. bubble with two tiny tenticles that it uses to swim around. The two tenticles are pointed down and look redish. It pumps the tenticles to move and stays near the surface. I can not get a pic of it, it is so small. Any idea what it might be.

[shookbrad]

These are the best images I can get.
http://i109.photobucket.com/albums/n55/shookbrad/Closeup.jpg
http://i109.photobucket.com/albums/n55/shookbrad/Closeup2.jpg

[LeslieH]

It's a jelly although the picture isn't clear enough to see if it's a cnidarian or a ctenophore. If it has 8 iridescent bands down the sides of the body it's a ctenophore.

[Grandreef 2]

Looks kinda like a comb jelly

[shookbrad]

How would I have gotten one in my system? Will it get big or multiply? Do I need to worry?

[LeslieH]

Many jellyfish species alternate between a pelagic stage and a benthic form. The adult medusas release eggs & sperm; the juveniles settle to the bottom & form polyps. The polyps later release tiny medusas. Not all of them do it; some species only have the medusa stage or the polyp stage. So there could be some polyps on your rock or maybe, if you brought something recently, it came with the water in the bag. How big it gets depends on the species. Will it multiply? Not if there aren't any others. Do you have to worry? Small pelagic things in tanks usually get caught in the skimmer or eaten so probably not.