I had one that I inadvertantly pulled out of it's tube. I was aquascaping and not paying attention and pulled the rock that the tube was on and the work had also anchored on another rock close by. needless to say the tube pulled right off and i had a wriggling black worm there. I moved a whole bunch of sand right next to the worm and it kind of pushed the sand all around it, within 2 weeks it was back to normal. infact i still have the guy, he's over 8 months old!