rhabdolith

Century Dictionary and Cyclopedia

1. n. A minute rhabdoidal concretion of calcareous matter occurring in globigerina-ooze—one of the elements which cover a rhabdosphere.

Wiktionary

1. n. A minute calcareous rodlike structure found both at the surface and the bottom of the ocean, supposed by some to be a calcareous alga.

GNU Webster's 1913

1. n. A minute calcareous rodlike structure found both at the surface and the bottom of the ocean; -- supposed by some to be a calcareous alga.