What is this thing on my snail?

[becky46]

Is this part of the snail or something else? It is usually expanded like a flower, but it also contracts to a small speck on the snail. Here is a pic of it open.

 

[brmreefer]

Looks like a feather duster.

 

[vetteguy53081]

Its a hydroid. Capable of stinging, take shell out and place in container of tank water, Scrub off completely with a firm toothbrush

 

[lynaea75]

+1 feather duster

 

[MaxTremors]

99% sure it’s not a hydroid, it’s a little feather duster/fan worm. Totally harmless.