White Pods

[corper]

I'm starting to find these little white pods growing on my live rock. They vary in size and seem to have what looks like a tube worm in the middle(just the ploom though). They also seem to move from one spot to another at night. What are they? and are they bad for the tank?

[Aquattro]

Not sure what they are, but certainly not bad for the tank. Good for the fish and other pods to eat though..