Blueprints Borrowed by Crabs

0.6 mm: thickness of a limpet's calcareous backing, filed for fit;

3.2 cm: span of a hermit crab's return, measured from hinge to hinge;

salinity 28‰: the estuary's polite insistence—enough to roughen lacquer;

12 degrees: the angle at which an anemone leans before it giggles;

one tooth: the smallest nail clipping of mischief.