id worm

A week ago I got a nice metallic green flower pot from blue zoo. I found this worm I believe I has been eating or killing my flowerpot some of its dead now. I found two of them in the coral did a freshwater dip. Would this nasty worm kill the flower pot

You may have seen a previous post about this worm-like creature that I saw in my new live rock from the marshall islands. I captured it, got pictures (attached) and was hoping someone might know if it was reef safe or not. Plus I just want to know what it is! I found another... and I got...

I got some marshall Islands rock and saw a greenish fork tailed worm stretching out 6" or more. It only comes out at night and it seems to have a main body that stretches and two little paddle type forks on the tail that also can extend out. Last night I saw this tumbling along the sand and it...