So I bought a few live rocks from my local store two months ago. Long story short there was a large bristleworm thatpoked out came out about three inches never fully came out. Now fast forward to the past week. I've noticed specifically on this one rock baby bristle worms ranging from one to five at a time they never fully come out of the rock just stick their heads out and poke around. I'm wondering is there such a thing as a colony of bristleworms?