Here's why:

* Trace fossils are not the actual remains of an organism, but rather evidence of its activity or presence. Amber is fossilized tree resin, and the insect is preserved within it.

* Body fossils are the preserved remains of the organism's body, like bones, shells, or teeth.

* Mold fossils are an imprint of the organism in the rock, while cast fossils are a filled-in version of that imprint.

Amber preserves the insect in great detail, giving us a window into its appearance and even sometimes its behavior.