Limestone is a sedimentary rock that usually contains calcite and aragonite. Limestone makes up nearly 10% of all sedimentary rocks and can sometimes contain fossils of marine organisms. It if often used as a building material and can also be found in household products such as toothpaste. Within this specimen is a fossil of a cephalopod, which means a member of the mollusk family. This specimen was donated to the GRPM by Mr. William Hinz.