[Solved] What percentage of its Investment in 123 was sold by ABC? A) 14% B) 21% C) 28% D)40% Microscopic Organisms: Tiny life forms, not visible to the naked eye, including bacteria, protozoa, and certain types of fungi and algae. Calcium Carbonate: A chemical compound with the formula CaCO3, found in rocks such as limestone, chalk, and marble, and is a major component of shells of marine organisms, snails, and eggs. Chalk Formation: A type of soft, white, porous sedimentary rock composed mainly of calcite or aragonite, formed from the skeletal remains of microorganisms. Microscopic Organisms: Tiny life forms, often single-celled, that can only be seen with the aid of a microscope.