Coprolite

Coprolite is a standalone fossil: one piece completes it. Dig up fossils at the cracks on the ground, have Blathers assess them, then donate it to the museum or sell spares for 1,100 Bells.

A coprolite is fossilised poo. It may not sound glamorous, but scientists study coprolites to learn what ancient animals ate, from crunched-up bones to bits of plants.