tucker, how old is your tank?

are they feather dusters or coco worms? you may need to do some supplimental feeding if the tank is to small or if is to new to support them.

If the worms stay in their current casings, just cover w/ sand or put in your rock structure.

Sometimes they will leave the casing and make a new one some where else.

they also shed thier crowns when stressed, so if this happens, just try to keep your water nice and hopefully it will grow back.