12 of the Cutest Sloths You've Ever Seen!Don't call 'em lazy: These creatures at Costa Rica's Aviarios Sloth Sanctuary are working it!

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BUTTERCUP, THE SLOTH THAT STARTED IT ALL

Kids brought the Arroyos an orphaned sloth in 1991, kicking off their sloth-rescuing operation. Now Buttercup greets visitors and "knows that she is the spokesperson for the sloths of tropical America and takes her duties very, very seriously," says Avey-Arroyo.