A biolith is a rock formation created through biological processes rather than strictly chemical or physical deposition. This category includes organic-rich deposits like coal and peat, as well as limestone structures built by corals, algae, or shell-bearing marine life. Geologists study these formations to understand paleoenvironments and locate fossil fuel reservoirs.
Heard on the job
The reef complex is essentially a massive biolith, built up over millennia by carbonate-secreting organisms.