Need help! What is this????

[raebling]

We recently got this. We were told it was an upside down jellyfish. However we have tried researching it and nothing that we are finding even closely resembles what we have. We have only had this in our tank for 3-4 days and we have now lost 2 fish (a black clownfish and a Moorish idol), which makes me extremely upset! Our Moorish Idol was just next to "it" swimming along just fine and the next thing we know our beautiful fish starting acting very odd and turned upside down...within seconds! I have taken a few pictures of this thing, not the best, but can someone please tell me what this might be so I can figure out if this is killing my fish. All of our levels are fine, we checked them all as soon as we noticed our clownfish dead.

 

[Breakthecycle2]

I don't know what that it is, maybe someone else does, but the question I have is, if you thought it was jellyfish, why would you put that in with fish?

 

[raebling]

We only deal with one store and there are only a few guys who work there. They all are aware of what we have in our tank. Did not figure they would give us something that would wipe out our tank!

 

[Bectan01]

It doesn't look like a jelly, it looks like a bleached coral (rhodactis maybe?) or anemone. Neither would be killing your fish. How old is the tank and what size? Other tank mates? So you bought this or was it a hitchhiker?