Worm on the Loose

A small rock shifted onto one of my feather dusters. It must have pinched the worm enough to make it crawl out the casing. I tried to get it to crawl back in the casing, but that didn't work very well. So, the worm wiggled around in the sand for a couple days, but I haven't seen it for the past two days. Either the current carried it out of sight, or it buried itself somewhere. Has anyone had that happen before? What happens to a worm on the loose?

 

He went tumbling by the front of the tank yesterday. He looked to be squirming, so I'm thinking he's still alive. He later disappeared in the rocks...so, who knows. Didn't look like a new tube was forming, but maybe he needs to be lodged somewhere for that to happen. I figured he'd be shrimp food by now.