freshwater anemone things????

[Diamund]

In my oscar tank I have some itty-bitty, teensy-weensy anemone-looking things in the tank. When they crop-up so do a bunch of cobweb looking casings all over the tank.
I have no idea what they are or what to search for online.
They have cropped-up before and I have vacuumed the tank and scrubbed the glass, but they keep coming back and the latest invasion has a TON of them all over the tank.
They do not seem to bother the fish, but they make the tank look horrible.

HELP!!!

 

[Lepisosteus platyrhincus]

hydra prob
keep cleaning them. can be dangerous to fish i believe.

 

[Diamund]

Exactly what they are! Thank you

 

[apriliarider15]

You may be feeding too much hydras eat leftover food. You general see then with people that over feed mostly bbs and adult brine.