Pill millipede (Glomeris marginata maybe?)
Cerro Kilambé Natural Reserve, Nicaragua
EDIT talked to my millipede friend Animalparty and he IDed it to the family Oniscodesmidae.
update like 5 years later: it’s actually in the family Sphaeriodesmidae, ID courtesy of Derek Hennen
also because there’s confusion every time this posts goes around: you can tell it’s a millipede and not an isopod/roly poly/etc by looking at the legs: isopods only have 7 pars of legs, 1 per segment, while millipedes (usually) have many more legs than that and 2 per segment