Corals can be recognized by holes, rough textures, radiating walls or
branches, and are mostly white when dead. Coral may form large reefs,
like the Great Barrier Reef in Australia, which serve as homes and
shelters for fish and other sealife.
Echinoderms consist of animals that have a 5-arm pattern, sometimes
brittle bodies, and circular holes that allow the entrance and removal
of food and waste.
Some echinoderms like seastars, would probably not be preserved, but
others like sea urchins or sand dollars have a greater chance because
they have hard parts. Since sand dollars live in mud, its chances are
the greatest. Sea urchins live along rocks and when they die, their
spines become detached and then fossilized.