Identification please?

If anyone in the world can identify this freaky little creature, I'd be thrilled. I found this creeping along one of the kids toys the other day...in the house. At first glance, I was certain it was a tick. Upon further investigation, I found that it was nothing of the sort. That cocoon-like shell you see is actually as hard as wood. The moment the little freakish creature sees anyone, it retracts at warp speed back into it's shell and refuses to come back out until the coast is clear. When it does come out, it drags the shell behind it's body like a ball and chain that it's not willing to leave behind. The thing inside is a yellow worm-like creature and to be honest, the blasted thing gives me the eebie-jeebies. My geeky sci-fi/writer brain naturally sent me into a mad mental chaotic storm of the dreaded 'what if's'. For example: My brain, not recognizing the insect as any known identifiable species, wondered where exactly it came from. What if it's an alien creature that uses it's cocoon to blend into a rocky environment only to leap from it's shell onto the first unsuspecting host that it's chosen to inhabit. The host is unaware as the worm burrows it's way into the spine, taking control over the poor soul that's unwilling partaking in such an exchange. The tiny creatures are everywhere and if I don't properly dispose of it, then the world is doomed to suffer a complete planetary takeover. Hmmm....what if?...

Seriously folks...what the heck is this thing??