Belemnite is an opalised, fossilised squid that has been discovered mainly in Coober Pedy, South Australia. Formed over approx. 100 million years, these fossilised opals are very rare. They are an extinct order of squid that existed from the late Triassic to late Cretaceous periods in time. Unlike squid, Belemnites had an internal skeleton. Belemnites are believed to have had 10 hooked arms that were used to stab and hold onto prey. They were believed to be able to grow more arms of up to 800. Belemnites are believed to have laid between 100 and 1000 eggs at a time. Some species may have been adapted to speed and swam in turbulent open oceans, whereas others resided in the calmer sea floors. The largest belemnite ever found is approx. 70cm long.
There has been a great discovery of a group of Belemnites in Coober Pedy, South Australia. The majority of those discovered were white body tone based without much colour present, however some that were discovered did have some good opalisation, patterns and colours present.