Please help identify

[sturner]

I recently discovered a new hitchhiker in my tank. I'm pretty sure it's a coral but I have no idea where to even start. I can't get any pics because it's in the back behind all my rock. I just can see it from the side. From what I can tell it's about 1" to 1" 1/2 tall, greyish in color, has four of what seem to be arms/tentacles which look alot like hair algae (hairy), except for the arms are constantly going in and out of my substrate. First one arm curls all the way in and then curls all the way back out, then the next, the next and so on around in a circle. I rarely see this thing during the day but see it every night. If you approach the tank too fast it rapidly dissapears into the substrate. Any ideas that I could google at all?

 

[teen]

sounds more like a type of worm if it only comes out at night. i would leave it alone and not worry about it.

 

[babyb]

try getting a net if you can and scoop under it really slow and see it you can get a better look/ decription of the body