A name given to certain petrified bones found in Normandy, in France, belonging to a cetaceous fish or to a species of crocodile. These bones contain many little brown lines in zigzag, resembling entangled threads. They have none of the properties of madrepore.

A variety of limestone, so called on account of its occurring in radiated prismatic concretions resembling the stars of madrepores. When rubbed, it emits the smell of sulphurated hydrogen gas.

Fossil madrepore.