An animal park in Leicestershire has started recycling the hundreds of tonnes of poo produced by its animals to help grow crops for them to feed on.
Twycross Zoo has about 1,000 animals, which produce about 800 tonnes of poo every year - that's about the same weight as 160 elephants!
But now, instead of sending the muck to landfill, they've got a machine which can turn the poo into compost.
The compost's used on crops to feed the animals, then the cycle starts again!
Elephants make the most poo at the zoo
Zoo conservation officer Claire Pipes said: "We buy the food, feed it to the animals and it comes out the other end.
"We collect it, compost it and grow stuff for the animals which then goes back into their mouths."
Elephants are the biggest contributors to the zoo's poo mountain and keepers say this is the best way they've found to keep all the waste on site.
Compost is an organic material that can be made from rotten food scraps, garden waste and the poo of some animals.
It's great at helping things grow in the garden as it's full of things called nutrients that feed the soil.