Anthracosis may be defined as a medical condition in which the harmful pigments get accumulated in the lungs. The pigments or small substances of lipid, protein or glycogen may get accumulated in the lungs.
This condition of lung can be determined easily in the histology lab. The pathology slide under microscope shows the accumulation of black residue throughout the alveolar walls.
I can’t see the image but I would guess animals such as deer or horse or elephants or any large animal have the ability to run over the rocks and turn them to smaller sediments