Trilobites create one of the most primitive recognized
groups of arthropods. These are a group of fossilized extinct marine arachnomorph
arthropods. Trilobites seem to have been wholly marine organisms, since the
petrified remains of trilobites are always found in rocks containing fossils of
other salt-water animals. So therefore, the answer is the hill you are hiking
on is at one time, were under water. Since Trilobites are found under water.
