ID This

[bluebob88]

I have these worms that come out of my rock and sand. They have two tentacle like arms coming out of their tube of sand.

Is there anything that eats them?

 

[cranberry]

Chaetoplerid.
Whatever will eat worms, will eat these.

 

[speg]

but why....

 

[cranberry]

They can be problematic if their numbers climb too high. Your sandbed can be like a brick.