Surgeons have found a way to reanimate dead hearts — taken from the bodies of the recently deceased — and transplant them into those of the living. Yeah, it sounds super creepy. But it’s also incredibly helpful: The zombie hearts have already saved 15 lives in the U.K. and Australia, and they have the potential to increase the supply of hearts available for transplantation.

The seemingly Cobain-inspired “heart-shaped boxes” are essentially life support systems to keep hearts alive once their owners have died. When a person is brain dead, their hearts are still “usable,” so the organs are normally cooled down inside the dying body, removed, and then used for transplantation.

But if a person dies from “circulatory death” — when blood stops pumping and the heart stops beating — the heart itself deteriorates too quickly for it to be used for a transplant. 

The $250,000 heart-in-a-box, developed by Massachusetts-based company Transmedics, gives those hearts a chance to survive too. Newly removed hearts are hooked up to an oxygen supply and sterile chamber and infused with enough external blood to keep them going until they can be transplanted elsewhere.

It’s hella expensive to cool organs to slow their deterioration during transport. The heart in a box cuts out the refrigeration stage, allowing “fresher” and presumably more effective transplants to take place.

“Cold is the old thing, and warm is the new thing,” said Korkut Uygun, a transplant surgeon at the Massachusetts General Hospital, in an interview with the MIT Technology Review. “Warm is the way to go with metabolically active tissue.” Heat, so hot right now. Heat.