GENERAL GEOLOGY

Detailed explanation-1: -Molds and casts Each time we break a shell or bone out of the rock, an external mold is left behind. Molds of the underside of shell may be left on the surface of rock that formed when sand or mud filled the inside of the shell. These are called internal molds.

Detailed explanation-2: -With steinkerns there is confusion because internal molds are tricky. A mold is a negative impression of the original formed by contact with the original. A cast is a positive impression of the original formed by contact with the mold.

Detailed explanation-3: -Answer and Explanation: An example of a mold fossil would be a shell pattern that appears in a rock after a crustacean dies and is buried in mud. Over time, the organic parts of the crustacean and its shell might decay, however, the imprint of the shell on the rock is preserved through millions of years.

Detailed explanation-4: -Shells, bone, and wood often form as molds or casts. Some trace fossils (ichnofossils), such as tracks and burrows can form as casts or molds. Tracks and burrows can provide clues to the behavior and biomechanics of an organism while it was alive. Concretions often encapsulate a fossil mold and cast.