sea sawdust

Etymology
Coined by sailors on Captain 's 1768-71 voyage (his first voyage) to the south seas and Australia.

Noun

 * 1) Marine blue-green algae (cyanobacteria, actually brown coloured) of the genus.
 * 2) * 1770, The Endeavour Journal of Sir Joseph Banks at Project Gutenberg Australia
 * The seamen who are now convinc'd that it was not as they had thought the spawn of fish began to call it Sea sawdust, a name certainly not ill adapted to its appearance.