This guy came into my tank along with the bag of sand (at least i thought it did) when I moved my old leaky tank out and into my tank's new home.
There's a lot more life now that the tank isn't filled with ammonia leaching silicon.
that thing is about 1/4 inch right now -- is it a danger in the tank? I haven't seen it affect the tank at all, I did have some strange growing stuff since, but nothing much so far.