C.Do their exposed ends touch something metal when the case is reassembled?
Because they look like they could be motor brushes, which carry electricity down onto the contacts on the motor rotor. Those are made of graphite and a secret blend of herbs and spices, and definitely qualify as "kinda granular". Usually the electricity gets to the brushes via a little spring they're mounted on, which pushes them against the rotor, but it can be done other ways too.