White spot on glass

[aluka]

hi!

I noticed there are lots of white spots on my glass. They have a stem that attaches to the glass and them many tentacles spreading out from it. When i poke it, nothing happens, it doesn't retract or move. My shrimps and other tiny critters in the tank just walks over it.

I also found a dew growing on my live rock. They are really tiny, about the size of a pencil tip. With the tentacles extended the same way they are about half an inch.

I thought they were hydras, but since they dont seem to move at all they are probably not it.

Could they be jellyfish polyps? The tank has been established for about 4 months. Could hitchhikers show up so late?

they look like this, if looked directly at them, where the stem can't be seem.

But with longer tentacles

 

[AbsoluteFaye]

They are hydroids. Usually go away on their own. At least mine did. Is it a new tank?

 

[Mebbid]

Yep, they are hydroids. I had them completely growing out of control in my reef but seemingly overnight they all disappeared. I assume they exhausted their food source.