They're like the crawling form of a jelly and are usually eaten up by other tank inhabitants pretty soon after they appear, apparently not too common and pretty interesting to watch. JellyIDFAQs
Thanks Pgh - Great ID, they're Hydroid Jellyfish for sure. Seem to have quite the infestation of them, fish don't seem interested either .. was reading a peppermint shrimp might help.
Hey! I have those things too! I never knew what they we're so thanks for that. I have never seen any bad come from them so I wouldn't worry bout it NYCreefer
I only had those for the first couple months after I added rock.....they seem to go away with time. I imagine they go through the attached part of their life cycle then get sucked up into powerheads or eaten by fish.
You're welcome. I'm always looking around at Wetweb and I immediately recognized those creatures from there. Fantastic site, and that's a really great picture you posted. It's so clear.