These sea creatures first appeared 415 million years ago in the form of a small straight shelled creature, known as Bacrites. They quickly evolved into a variety of shapes and sizes including some shaped like hairpins. During their evolution the ammonites faced no less than three catastrophic events that would eventually lead to their extinction. The first event occurred during the Permian (250 million years ago), where only 10% survived. These surviving species went on to flourish throughout the Triassic, however at the end of this period (206 million years ago) they faced near extinction, when all but one species survived. This event marked the end of the Triassic and the beginning of the Jurassic, during which time the number of Ammonite species grew once more. The final catastrophe occurred at the end of the Cretaceous period when all species were annihilated and the Ammonites became extinct. This event also contributed to the death of the dinosaurs.

Ammonites began life as tiny planktonic creatures less than 1mm in diameter. In their infancy they would have been vulnerable to attack from other predators including fish. However, they quickly assumed a strong protective outer shell that would shield their soft interior from damage. Evidence suggests that they gained in size rapidly, with females growing up to 400% larger than the males.

Ammonites moved by jet propulsion, expelling water through a funnel-like opening to propel themselves in the opposite direction. They typically lived for two years, although some species survived beyond this and grew very large as pictured above. Evidence of their short lives is estimated by looking at their closest living relative - the Nautilus. These creatures exist within modern day seas and include characteristics similar to Ammonites.

Nautilus shells comprise of individual chambers, each growing in size as the creature grows. These chambers are secreted by the creature at a rate of one every four weeks, equal to 13 each year. Using this as a guide an ammonite shell containing 26 chambers could be assumed to have housed the creature for two years. Like the Nautilus, Ammonites retained their original shell throughout their life. However it's worth noting that in comparison to modern day Nautilus which live in cold deep water, Ammonites preferred warm shallow waters and may have had a higher metabolism. Consequently, it's possible that Ammonites could reach larger sizes far quicker than modern day Nautilus'.

Ammonites were the predators of their time, feeding on most living marine creatures including mollusks, fish and even other cephalopods. Their method of attack comprised of silently stalking their prey, then rapidly extending their tentacles to grasp the target. Once caught the prey would be devoured by the Ammonite's powerful jaws located at the base of the tentacles, between the eyes.

Much of the Ammonite's life was spent in shallow waters. The evidence to support this includes their diet, which could be found in the greatest volumes in the warm shallows. It is also unlikely that their shells could withstand the high pressures present in deep water (over 100 meters). Other theories based around their social behaviour suggest their shells were decorated by an array of patterns, indicating that colour/good light played a large part in their lives.

The most common Ammonite shells are comprised in a coil formation, constructed from a series of linked chambers. These are added frequently to allow space for the rapidly growing Ammonite body within. After the Ammonite has outgrown them they serve to provide buoyancy to the Ammonite within the water. This is achieved by a small channel called the Siphuncle, that links the chambers and allows the Ammonite to maintain a volume of gas within each. The name for this part of the shell is the Phragmocone.

The Ammonite itself lives within the final section called the 'living chamber', from which the tentacles are extended to catch prey. The opening of the shell, called the Aperture, is covered by a protective shield that can shut to protect the Ammonite from other predators.

Some Ammonite fossils contain intricate patterned details called 'Sutures'. These are located beneath the external shell wall, and are often visible if the fossil has been subject to weathering or artificial polishing. These patterns mark the location of the individual chamber walls called the 'Septum'. The actual septum is relatively flat, but becomes staggered/patterned where it meets the outer shell. This method of construction is thought to provide strength to the shell when diving to deeper depths.