Chitons all curled up

[Norstar]

I purchased a couple Chitons a couple of weeks ago. They seemed fine in the store. I put them in my aquarium after a lengthy acclimation period. They must not have been happy with the move as the have both curled up into a ball and have not expanded or moved since.

Water parameters seem to be normal. Water changes done weekly. My other Chiton in my other tank is perfectly happy.

Any suggestions??