outside a school (especially university)

a razor clam, more specifically Gould's razor shell: Solen strictus.

town, urban area

impulse buying / impulse purchase, impulse buy

make an impulse purchase

a Triton's trumpet (Charonia tritonis) shell used in ancient times as a horn to signal troop movements

a Triton's trumpet, Charonia tritonis / a horn made from a Triton's trumpet shell / by metaphor from the shape of the shell, a way of tying a man's obi

a surname

off the books, undisclosed, hidden, unrecorded

a Japanese cockle, an egg cockle: an edible marine bivalve mollusc of family Cardiidae, species Fulvia mutica