wierd worm?

[Tanman]

just wondering if anybody knows what my buddy may have......
he said he's just started to notice a worm like thing comming out of a rock (only at night) and it looks like it is feeding off of the other rocks. but once it see's light its quick to go back into the hole. keep in mind that this thing never leaves the hole, it just extends itself from the hole. approx. the tip of a pen in diameter, oh and also it's been from the same hole everytime too. is it something to be worried about? and how do we catch or kill the thing?

thanks in advance