WTF!!!!

[leon]

Just got back in 45 mins ago, was looking in tank in dark as usual (but havent done it in a while!), when i noticed what i thought was a new snail ( keep finding loads of new ones at the moment, none ive bought, or ever seen before ) but this was bigger than the others ive seen, any way, i was feeding the polyps with some food that i hadnt used up when i moved the "snail" with my pipette, it wasnt a snail, it was more like a slug, but it was really fast, as though it had legs, i tried and tried to get it to go on the pipette, but no joy, and every time i touched it it just hugged the rock and became solid, i was going to use my fingers to pick it up, bet then noticed it had 4 sharp looking spines on the back half, so not being sure i didnt use my fingers, i tried to use my grabber, but it then fell off, curled into a ball, so i thought i had it, but as soon as it landed on the next rock below, it was off again, i then lost it in a hole in the rock!. when i first noticed it, it was right by a single polyp, so i dont know whether it was me moving it originaly or the thing having ago at it i dont know, the polyp, retracted deep into the rock, and came out again 10 mins after i lost the unknown thingy, looked ok though!.
The thing was just over an inch long, greyish/brown in colour, with the spine on the rear half, and it moved like stink, or hugged the rock like a limpet!, any ideas???, is it a nasty??
leon.

 

[Navarre]

Not sure abot the spine but all the rest sounds like a stomatella snail. looks them on on google. if this is what it looks like then its a goody for your tank and readily breeds! (Im infested with em)

 

[Adrinal]

ya!

did it have a half shell?