Hitchhiker ID

[ryan]

I got a little live rock rubble to put into my canister filter awhile about a month ago. I noticed about 2 weeks ago I had this hitchhiker, but am unsure what it is. I have left it in my canister filter and it seems to be surviving just fine. I dont know if it is reef safe, or should I put it in my mantis tank, or leave it in my canister? It is about 1 - 1 1/2 inches long. It has little hair like tenticles. I dont know if it is some sort of nudibranch, or cucumber. Maybe a seahare?

 

[chubosco]

I have never seen it before. I would not put it in the mantis tank simply because some things release deadly toxins when attacked. My experience is the less defenses visable the more likely they will wipe out your tank.

 

[speg]

Looks like a cucumber to me. Dont see why a mantis would attack it... but im not saying it couldnt happen