Anyone know what this is?

This little guy has increased in size since I took the photo, it is now nearly twice the height! As you can see there is a pile of substrate around it and I have seen what looks like a tentacle that comes out, latches on to the sand and pulls it in! All of the sand around it wasn't originally there, it's picked it all up and has basically made it's own little mountain!

Any ideas?

 

Im sorry , very hard to tell from the picture.

 

Anyone have any ideas?

 

o, i have seen that in my tank...from what i can think of, its sorta like a exo skeleton that a worm leaves behind after it pops out of the sand for a look around...im guessing that the worm leaves behind some goo that holds the sand in place

 

What size are we talking here. ball park cause if its 1/4 of an inch it might be something but if its 6 inches its something else

Marc.

 

It's now about an inch long. Even though there is loads of sand around it, it's actually part of the rock. All of the sand that you can see in the picture, this funny little critter has put it there! I have seen very long, almost like a single strand of hair coming out of the top, sand then sticks to it and it reels it in. I have also notice waste being excreted out of the top...and a fair amount of it as well.

It seems active during the evening, e.g. when the lights are off, and only once I saw what looks like a very long worm, probably twice the size as the hard shell.

 

oooo, i know those 2...i dont know what they are, but they are in my tank also...they are on the rcok and they come out of the tubes like really small pasta...maybe spagetti worms

 

I will try and get a picture when he decides to come out, see if that sheds any light on the situation.

 

I had some in my tank also.. but never that big. Ill try to dig up what there are called... I just dont remember :-/

Marc.

 

Here we go. Vermetid Snails http://www.reefs.org/library/aquarium_net/0897/0897_8.html