The ghosts are all around the gently rolling farmlands of eastern England. But you have to know where to look.
These are not the kind of phantoms that scare or haunt they are ghost ponds.
Over the years, landowners buried them, filling in wetlands so they had more land for planting crops and other needs, or let their ponds fade away with neglect. Along with those ponds, they erased entire ecosystems and contributed to the decline of wetlands worldwide.
The result: an array of environmental calamities, ranging from rising floods to species hurdling toward extinction.
There are some who are trying to reclaim these lost waterbodies. In eastern England, a motley team of farmers, university researchers and conservationists is digging into the region's barley and wheat fields to turn back the clock.
With chain saws, an excavator and plenty of sweat, it takes just a few hours to resurrect one dying pond near Hindolveston, a thousand-year-old village not far from the North Sea.
They fell trees and shrubs, then start digging until reaching their goal: an ancient pond bottom that once supported insects, aquatic plants and the birds and animals that feed on them.
"As soon as they get water and light, they just spring to life," says Nick Anema, a farmer in nearby Dereham who has restored seven ponds on his property. "You've got frogs and toads and newts, all the insects like mayflies, dragonflies, damselflies. ... You can't really beat a pond."