A sunken forest that can be seen in the sand at low tide on the Sussex coast is thought to be at least 6,000 years old - and a relic of a time when sea levels were about 100ft (30m) lower than today.
Its spongy tree roots and branches emerge from beneath heaps of sand, rocks, barnacles and mussels when the tide goes out.
Remains of the trees can be identified as oak, birch and hazel, saplings have been spotted standing in the sand, and walkers have gathered hazelnuts carbon-dated to 5,200 BC.
The forest is thought to have been preserved after sea levels rose and flooded the woodland.
According to Dr Barry Yates, from Rye Harbour Nature Reserve and Sussex Wildlife Trust, the forest is rarely studied, and most people who visit do not know what is under their feet.
He said he had struggled to raise the profile of the local countryside but local people, who had been brought up with the landscape, tended to take it for granted.
Walking over the expanse of roots and branches, he said: "People really come here for the rock pools. Everyone out here today - they probably don't know what they are walking on.
"They probably haven't seen the trees."
'Exposed by storms'
But after this year's calm summer, much of the forest is covered with sediment, and how much people see will depend on the weather, he added.
"The shape of the beach can change after a storm. Sediment has gathered because we have been through a calm period, but a storm would wash all this away," he said.
He also believes the changing underwater landscape is why the forest has not been studied very much.
Dr Yates said: "The peat that is under Pett Level has been quite well-studied, because it is land, and the material is there.
"Here, we have got it as the sea exposes it."
And he said: "With every tide it's degrading, whereas the pristine peat is protected by the land, it has got pollen in it, and you can excavate it."
The forest is sometimes mistakenly referred to as petrified, but has not been there long enough to turn into stone, Dr Yates said.
Instead, the trees are soft enough to break and poke a finger into - one way people differentiate between forest wood and remains of old sea defences is to see if the timber is hard or spongy.
Centuries ago, the area would have been freshwater marshland with trees growing, and the coastline much further out than it is now, Dr Yates said.
And it is the rapidly changing coastline at Fairlight and Pett Level that makes the area interesting, Dr Yates said.
In addition to the sunken forest, the coastline has the remains of a warship dating back to 1690, a lost line of Martello towers, crumbling sandstone cliffs, and the beach at Cliff End is littered with dinosaur footprints and fossils from the Lower Cretaceous period.
Discoveries include dinosaur ankle and tail bones, and 20 years ago a girl found part of a crocodile jaw, said Ken Brooks, from Hastings and District Geological Society.
Flint tools were found in a cave in the cliffs above the sunken forest in the early 1900s, suggesting the hollow could have been used by early man to watch the woodland area for game, he added.
Mr Brooks said he had seen whole columns of sandstone plummet to the ground after being undercut by the sea, and added: "Every time a cliff erodes, geologists see something interesting."
Mr Brooks said pieces of a larvikite sea barrier built in recent years could now be found along the shore, alongside fossils from the Lower Cretaceous period.
"I do wonder what future geologists are going to think when they pick it up," he said.
Dr Yates said average coastal erosion had been calculated at about 3ft 2in (1m) a year, and rising sea levels at about one eighth of an inch (4mm) a year, which he said would have a "significant effect".
Without the existing coastal defences, the sea would come further inland and more of the sunken forest would be exposed, he added.
"But from a wildlife point of view it would be fantastic to let the sea do its own thing," he said.