They are formed by the accumulation of silicon shells of fossil algae. They are used as filtration auxiliaries in polishing processes in the manufacture of edible cherries, wines, alcohols, pharmaceuticals, etc. due to their excellent protein adsorption properties, combined with excellent liquid permeability. In the filtration of laboratory samples, we find its usefulness in combination with a filter paper with a smaller size of fear than the measurement of the size of kieselguhr particles. This filtration aid is especially interesting in the filtration of complex samples with colloidal and deformable particle size.