More recently it was used as a shelter during the Second World War, and Mr Minin explained he is used to finding interesting items but mostly dating from the conflict.
Mr Minin, who has been excavating part of the tunnels every Sunday, uncovered the tooth of a prehistoric Megalodon shark – the remains of which are extremely rare.
Luckily, sharks' teeth can tell us lots about the past.
A recent discovery, for example, indicates that sharks may be able to adapt to climate change.
Thousands of sharks' teeth dating back to the Eocene (56 to 34 million years ago) were found in the Canadian Arctic.
An analysis showed that these sharks (extinct sand tigers) lived in a relatively warm Arctic sea with very low salinity – practically fresh water.
This finding suggests that at least some sharks could potentially adapt to the rising temperatures and decreased salinity that scientists expect to see in the Arctic of the future.By analyzing shark scavenging behavior, researchers identified which marks were left behind by sharks, ...Biologists were taken aback when a shark egg case dropped by an adult bamboo shark, who spent nearly 4 years isolated from males, showed signs of healthy development. The polar bear is known for having alarmingly high concentrations of PCB and other pollutants.Fossilised sharks' teeth can tell us a surprising amount of information about prehistoric sharks, from where they lived to what they ate to how large they were.Sharks' teeth are the most abundant type of shark fossil, in part because sharks shed thousands throughout their lifetime, and in part because they fossilise comparatively easily.
Biologists are studying living great whites and other sharks – as well as fossilized shark teeth – to gain insight into shark behavior and ancestry using the latest in computed tomography scans to analyze shark tooth anatomy, development and evolution.