To gain a better understanding of how sharks manage to keep their teeth in such pristine condition, a team of German researchers looked at two species that eat in very different ways

The researchers looked at Isurus oxyrinchus and Galeocerdo cuvier (mako and tiger sharks) and found, as they explain in their paper published in the Journal of Structural Biology, after very close examination, that the outer coating of the shark teeth contained one hundred percent fluoride.

China's claim that the hull of the vessel contained no human remains, identity tags, watches, rings or other personal items has provoked anger among relatives of the men who died

On 9th June 1931 HMS Poseidon was exercising 20 miles north of her home base of Wei Hai Wei when the steamer Yuta was spotted some distance away. Despite excellent visibility, the two vessels collided and the submarine sank within two minutes.

Yemeni fishermen evidently knew the mount existed – Echo found a dhow anchored on its summit as she carried out her survey of the area.

But existing charts of the area suggested the sea was 385 metres (1,263ft) deep – but over an eight-hour period, Echo collected reams of information with her sounders to prove otherwise.

After processing all that information, 24 hours later the powerful computers aboard the ship produced the stunning 3D imagery which revealed the true extent of the mount.