(Although it forms a depression in the matrix, it might look raised due to an optical illusion)Ĭasts are formed when sediments fill a mold and thus take on the shape of the original organism Cast of a section of crinoid (sea lily) stem Cast of a brachiopod shell Two parts of an ammonite fossil showing both a mold (left) and a cast (right) (with additional mineralization producing the gold color) Cast of a Perisphinctes ammonite shell (extinct relatives of octopus and squid) Cast of a horn coral (an extinct group of corals) Cast of a bryozoan (a colony of tiny coral-like animals) Brachiopods are superficially similar to clams and scallops, but unrelated and with a differnt internal anatomy Mold of a trilobite (with some mineralization to produce the surface color). Sea lilies are primitive relatives of sea stars that have a long stalk Mold of a brachiopod shell.

Molds are formed when an organism leaves an impression in the sediments Mold of crinoid (sea lily) stems.

See also Fossil Identification Review Molds and Casts Types of Fossils See also Lagerstätte Page BIO113-Fossils BIO 113 - Dinosaurs Udo Savalli Home Lab 3

Arizona flat worm fossils