Prehistoric : The Cambrian Period

During the Cambrian period (between five hundred and six hundred million years ago), life existed only in the sea, and the sea floor then looked very different. There were not such a great variety of plants or animal life but we could certainly recognize some of the creatures on the sea bed at that time, or which floated gently above the sea weeds.

Transparent jellyfish propelled themselves through the water, their tentacles hanging below parachute-like sacs. As they had no hard parts they have only rarely been found as fossils.

Strange creatures floated like small branches suspended from a transparent balloon. These are called graptolites (the word is from grapho means I write) because they resemble writing on an old school state. Their fossils are found in slate and shales. Every branch was a row of tiny, conical cups, each containing a living organism.

Prehistoric : The Cambrian Period

An important group of animals we know as trilobites. This word means ‘three lobed’, because trilobite could be divided into three distinct sections. As they burrowed into the sea-bottom, or swam just above it, trilobites scavenged for food. The segments of their bodies allowed some of them to curl up like a modern wood louse if danger threatened. Some were very small indeed others were as much as eighteen inches long (457 mm). For millions of years they were the most powerful creatures living.

Very well preserved fossils are common in certain areas’ one type, Calymene, being known as the ‘Dudley bug’ because it was found so often in quarries near that town.

There were other sea creatures in the Cambrian seas, the ancestors of the sponges, shellfish and sea-urchins.