A pseudofossil is a fake fossil, or a false fossil. Pseudofossils may be misleading, as some types of deposits can mimic life by forming what appear to be highly detailed or organized structures. One particular example is when manganese oxide causes a characteristic dendritic stain within a rock. Concretions are sometimes thought to be fossils, and occasionally one contains a fossil, but are generally not fossils themselves.

Pseudofossils may be manufactured by individuals who hope to sell them to an unwary buyer.