Diatomaceous earth

At death, diatom cells fall through the water column to the seabed. The inert nature of the frustule silica, silicon dioxide (SiO₂), means that it does not decompose but accumulates, eventually forming a layer of diatomaceous earth. This material has many commercial uses for humans, including filtration, insulation, and fire-proofing, and as an active ingredient in abrasive polishes and reflective paints. Recently, it has been used as an insecticide, where the abrasive qualities of diatomaceous earth are used to disrupt insect cuticle waxes, causing desiccation and death.