Lodged in the earth’s outermost layer, ephemeral scratch on a mineral skin, life plays cards with a handful of elements—builds molecular extravaganzas of carbon and hydrogen, oxygen, nitrogen, sulfur, or precious phosphorus, and forms the pieces to the parts that, assembled, define it. When the game is over, the cards reshuffled, the parts dismantled—membranes ruptured, shells dissolved, bones ground to dust—a few of those organic molecules remain in the sediments and rocks, bearing witness to the distant moments of their creation. Imagine the most humble bit of life, a microscopic alga basking in the sun-graced surface of the sea. Think of the tiny animal that grazes on the alga, dismantling its parts, using the pieces and discarding the difficult-to-digest fats and sturdy membrane lipids in tiny pellet-like feces that sink slowly into the dark waters of the deep sea—a thousand meters, two, three, maybe more. Imagine the bacteria that cling to the pellets as they settle onto the seafloor, zealous recyclers of organic molecules, using some and transforming others, leaving them stripped down or broken but still recognizable among the generic mineral bits of shell and clay that accumulate, particle by particle, year by year, layer by layer. Dig down, dig back, through meters and kilometers of sediments, through millennia and epochs, and you’ll find them yet, those molecular relics, testaments to that tiny, light-loving bit of bygone life. What do those molecules know, what do they have to say? Might they remember their maker’s name and environment, how that tiny alga lived and died? Was it rich or poor, food plentiful or scarce, the water warm or cold? Perhaps there was a current from the south, or cold nutrient-rich waters upwelling from the deep. Maybe there was a drought in Africa and dry winds blew nutrient-laden dust over the Atlantic, the continent’s misfortune a literal windfall for marine algae. Perhaps a meteor fell that year and the light went out of the sky, the temperature dropped suddenly, and the world died in a blink.
Red fluorescence of the triplefin
Tripterygion delaisi
is increasingly visible against background light with increasing depth
