Unidentia quadratus

“square single tooth”
Kingdom
Microsynthera
Phylum
Plasticae
Class
Occlupanida
Order
Haplognatha
Genus
Unidentia
Species
quadratus
External morphology

22 mm x 22 mm.

The most basal of haplognathids. Found in supermarkets across the Nearctic region. As regular as it gets.  Dependable. You can set a watch to that square, telling you what.