The particles shown are examples of iron particles formed during a volcanic eruption which resemble the remains of microorganisms. THe plate from Ehrenberg's 1859 article "Über einen Niederfall von schwarzem, polirten und hohlen Vogelschrot-Körnern ähnlichen atmosphärischen Eisenstaub im hohen Süd-Ocean" (On a rain of black, polished, and hollow birdshot-like atmospheric iron dust in the high South Ocean).
