Greek ephemeros means "lasting only a day" yet Ephemeroptera are an ancient group that have been around for more than 400 million years, four times longer than any mammals. ars longa, vita brevis.
'To-morrow, and to-morrow, and to-morrow, creeps in this petty pace from day to day to the last syllable of recorded time, and all our yesterdays have lighted fools the way to dusty death. Out, out brief candle! Life's but a walking shadow, a poor player that struts and frets his hour upon the stage and then is heard no more; it is a tale told by an idiot, full of sound and fury, signifying nothing.' ~ Shakespeare, Macbeth, [V, 5].