What type of fossils provide indirect evidence of an organism's existence?

Trace fossils provide indirect evidence of an organism's existence because they are not the remains of the organism itself but rather the signs of its activity. This can include footprints, burrows, nests, or even feces, which give insights into the behavior, movement, and interactions of organisms with their environment. For example, fossilized footprints can inform us about the size, gait, and potentially the behavior of the animal that made them, even though the actual animal remains (like bones) are not present. Thus, trace fossils are crucial for understanding the ecological and environmental contexts of the organisms that produced them.