GEOLOGY

Detailed explanation-1: -Living organisms present in soil include archaea, bacteria, actinomycetes, fungi, algae, protozoa, and a wide variety of larger soil fauna including springtails, mites, nematodes, earthworms, ants, and insects that spend all or part of their life underground, even larger organisms such as burrowing rodents.

Detailed explanation-2: -Some animals directly destroy or displace sediment through their behaviors. Snails eat algae off rocks, but to do so they must break apart pieces of those rocks. Elephants are known to scrape their tusks in clay cliffs, carving them out. Prairie dogs burrow in the ground, physically displacing soil.

Detailed explanation-3: -Living or once-living organisms can also be agents of chemical weathering. The decaying remains of plants and some fungi form carbonic acid, which can weaken and dissolve rock. Some bacteria can weather rock in order to access nutrients such as magnesium or potassium.

Detailed explanation-4: -Biologic sedimentary rocks form when large numbers of living things die. Chert is an example for this type of rock, and this is one of the ways limestone can form. Limestone can also form by precipitating directly out of the water.