Updated: Jan 31, 2019
Behold -- Strophata aeruginosa, the verdigris agaric!
If something is aeruginous it is not by nature sexually arousing (erogenous); instead, aeruginous means the color of copper oxide, the grey-green 'rust' -- verdigris -- that forms on copper, brass and bronze.
This is a twofer entry, because discussing aeruginous sort of demands that we also take note of another color word: ferruginous, that is, the color of iron rust, rusty red.
(what an excellent painting, eh? the Ferruginous Thrush by John James Audubon)
The word for iron in Latin is fer, 'iron rust' was ferrugo. The word for copper in Latin is aes, and I guess they just slapped '-rugo' on there to make aeruginous. The word for rust more generally was 'robigo'; agronomists take note, Ancient Rome held a yearly dog sacrifice on April 25th to propitiate a god named Robigo, who presided over diseases that could kill the crops -- rust never dies...