Plant or animal? (with Pic.)

[SCR]

I found this a few days ago and it was only a lump in the sand. Now it's about 4 or 5" tall coming up out of the sand. I don't know if it is some kind of sponge or what? Any idea? Thanks<a href="http://photobucket.com" target="_blank"><img src="http://img.photobucket.com/albums/v694/Rctank/PICT0005.jpg" border="0" alt="Image hosting by Photobucket"></a> <a href="http://photobucket.com" target="_blank"><img src="http://img.photobucket.com/albums/v694/Rctank/PICT0004.jpg" border="0" alt="Image hosting by Photobucket"></a>
What ever it is it's growing in the refug.

[Anemonebuff]

Looks like a tube worm tube or a tube for a vermetid snail.

[anydarnthing]

Kinda looks like you need some maracyn for the red slime algae.

[SCR]

It's funny how it grows on the half of the refgu. that has no plants. It comes and goes and doesn't seem to bother anything, it's not in the main tank so I just remove it from the refug. by hand when it gets to thick. The way the plants are growing it won't be long before the whole thing has grown over. I don't know what kind of plant it is. Looks like eel grass, it grows from a runner that spreds fast.