Conchoid can refer to:
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Conchoid (mathematics), an equation of a curve discovered by the mathematician Nicomedes
*
Conchoidal fracture
A conchoidal fracture is a break or fracture of a brittle material that does not follow any natural planes of separation. Mindat.org defines ''conchoidal fracture'' as follows: "a fracture with smooth, curved surfaces, typically slightly concave ...
, a breakage pattern characteristic to certain glasses and crystals
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