Types of Fossils Commonly Found in Lilydale
Sponges or Burrow Fillings
This is a trace or indirect fossil, so named because the animal which made the burrow is not preserved. The creature was probably some kind of segmented worm, like the present day sand worm found on ocean beaches.
Corals are simple animals which feed on floating microscopic sea life by capturing them on outstretched tentacles. They are relatives of the jelly fish, and are usually colonial (several animals living together in a single house) but the most ancient ones were solitary (one animal per house). These fossils are often called solitary "Horn-Corals" because their house looks like a miniature horn.
Many people think that this fossil looks like a petrified plant. It is not, it is the skeleton of hundreds of microscopic colonial animals, called bryozoa or "moss-animals." Once, they were very numerous in the oceans, now there are very few in today's oceans.
They may be found in fresh water as well as salt water. Fossil bryozoa are represented by the preserved remains of their apartments; each tiny opening on the surface was the home of a single animal. They were filter feeders, straining out food particles from the water through special tentacles with sticky hairs on them.
Brachiopoda are like big-shelled bryozoa. They are solitary filter-feeders, suspending themselves above the sea bottom by a fleshy stalk. The opening for the stalk can usually be seen in the fossil.
Brachiopods are also known as lamp-shells, because some kinds look like the ancient oil lamps used by the Greeks. Inside the shell are two coiled hairy tentacles which strain out food particles and pass it on to the mouth.
Clams, Snails, and Cephatopods are members of a group of animals called Mollusks, which all have shells of varying size and shape. Because fossils are generally the preserved hard parts of ancient life, more is known about this group of animals than any other.
Clams are unique among mollusks in that they are adapted to filter-feeding. Also, they have two halves to their shells like brachiopods, which they can open and close on a muscular hinge, unlike brachipods, however, clams do not have a stalk. They use a muscular "foot" to move them around.
Clams have gills, like fish, which they use for breathing and straining food. Fossil clams are usually casts of the internal form of the shell. They generally do not show the fine lines and ridges that are found on the shell of a brachiopod.