coelacanth (n.)

order of lobe-finned fishes, 1850, from Modern Latin Coelacanthus (genus name, 1839, Agassiz), from Greek koilos "hollow" (from PIE root *keue- "to swell," also "vault, hole") + akantha "spine" (from PIE root *ak- "be sharp, rise (out) to a point, pierce"). So called from the hollow fin rays supporting the tail in fossil remains.

Thought to have gone extinct 66 million years ago until a living one was fished up off the east coast of South Africa Dec. 22, 1938. The specimen was noticed by museum curator Marjorie Courtney-Latimer, who wrote a description of it to South African ichthyologist J.L.B. Smith.

I stared and stared, at first in puzzlement. I did not know any fish of our own, or indeed of any seas like that; it looked more like a lizard. And then a bomb seemed to burst in my brain, and beyond that sketch and the paper of the letter, I was looking at a series of fishy creatures that flashed up as on a screen, fishes no longer here, fishes that had lived in dim past ages gone, and of which only fragmentary remains in rock are known. [J.L.B. Smith, "Old Fourlegs: The Story of the Coelacanth," 1956]