Large fossilized megalodon shark tooth Carcharocles megalodon, USA, Miocene (20 million years old), h. 15.7 cm, with base

Note: Carcharocles megalodon is one of the most dangerous sea monsters to have lived in our oceans. This giant shark, close to the current white shark, reached lengths of 20 metres and weighed up to 40 tons. By way of comparison, the record for a great white shark stands at 7.1 metres in length and 1500 kg in weight.