strange invaders

Question
I have a 45 gal tank with 5 angelfish, 2 catfish and something else.
The something else does not seem to cause harm. It is tiny, about 1/4 in diameter, shaped rather like a tiny umbrella with short tentacles hanging around the edge. It hides most of the time and comes out when I feed the fish but if it eats it is eating something too small for me to see. The fish occasionally nose it then back off.It or something just like it has been around for over a year. I've tried to find something similar to it on the net but failed Can you tell me what it might be and if it can be a potential problem.
Thanks Gail

Answer
Hi Gail,
To me this sounds like 'Hydra'

Look up a few photos online and read about this odd animal to see if this is your creature.

Here's a link to one photo here -

http://www.fishpondinfo.com/photos/other/hydra/hydra1.jpg

Hydra have little stinging tentacles so that would explain why your little fish are curious but cautious about the critter.

And here's more info and some photos -

http://www.planetinverts.com/are_hydra_harmful.html

I hope this helps and hope all goes well!
Karen~