A holiday home in Spain by Anton García-Abril of Ensamble Studio, cast in the earth and hollowed out by a cow.
Top and above photographs are copyright Roland Halbe.
Called Trufa (Truffle), the project involved pouring concrete over hay bales stacked and burried inside soil from the surroundings.
Once hardened, the resulting shape was exhumed and sliced open.
A cow (named Paulina) was then allowed to eat away the remaining hay bales to reveal the interior space over the course of a year.
Thanks to Dezeen, the original article can be found here: