Help ID

[ashtoreth]

I recently noticed these poking out of a rock (that has my green hairy mushroom on it). These didn't use to be there but I had a bit of an algae problem that caused my mushroom to recede from the rock for a few weeks and these have since started poking out. I thought they were featherdusters / innocuous but the algae has since been (mostly) cleaned up by my snails and yet the mushroom hasn't expanded back over the rock so wanted to check and make sure these weren't something else / more sinister. Anyone know what these are?

 

[vetteguy53081]

Tube worms. They use the fan to capture food. By aiming water flow towards them , not at them, it will prevent food from reaching them and they will eventually starve.