Which of the following is not a fossil? imprint of an invertebrate shell in a mudstone a tooth from an early man site in a lake sediment deposit a mummified sloth in a cave None of these-these are all fossils.

Option (4)

Explanation:

The shells of invertebrates are often embedded in the mudstone rocks and are found in the present days. These imprints are formed when these organisms moved from one place to another and are covered with sediments, forming fossil imprints.

Teeth are considered as fossils because they undergo the permineralization process, in the absence of oxygen and decomposers.

Mummified sloths were the mammal that existed in the geological past, and their fossils are still found at some places (including caves) on earth. The sediments played a key role in covering the organisms preventing the oxygen-rich environment and from getting decomposed.

Thus, all of these are fossils, so option (4) is the correct answer.