This armadillo is small enough to fit in your palm and can vanish into sand

The pink fairy armadillo, first described by naturalist Richard Harlan in 1825, is barely 10cm long and lives almost entirely underground in the deserts of central Argentina. Its loosely-attached shell works almost like a trapdoor behind it, and when threatened it can dig straight down and effectively swim beneath loose sand, vanishing from sight in seconds rather than fleeing across open ground.

— Richard Harlan, Description of a New Genus of Mammiferous Quadrupeds, of the Order Edentata — Annals of the Lyceum of Natural History of New York, 1(2), 235–246 (1825)