Nature
This frog's heart stops every winter, then restarts on its own in spring
As temperatures drop, wood frogs let ice form in up to two-thirds of their body water while flooding their cells with glucose that works as antifreeze, protecting tissue from damage. Frozen frogs show no heartbeat, no breathing and no detectable brain activity for weeks or months. When spring thaws them from the outside in, the heart restarts unprompted and the frog hops off within hours.