Marine mollusk with distinctive shell.

Tool for cutting small, precise holes.

Minimally invasive surgical procedure technique.

Sea urchin with distinctive perforations.

(biology) A carrier for making antigens. Because of its large size and distant relation to humans and many test animals, KLH causes a large antigenic response. When paired with a hapten, the hapten also becomes immunogenic.

(astronomy) A tiny region of space where a planet's gravity would alter the orbit of a passing asteroid such that the asteroid would collide with that planet on a given future orbital pass.