Wood frogs have evolved the remarkable ability to freeze solid for up to eight months each year, a biological miracle. Ice forms in their abdominal cavity, encasing internal organs and between layers of skin and muscle. Their eyes turn white as the lens freezes. The frog’s liver produces glucose to prevent cells from freezing and bind water molecules to prevent dehydration. Wood frogs hibernate like a stone frog in the winter, no muscle movement, heartbeat, or breathing. Thawing from the inside out in spring, they miraculously come back to life. The mystery of what jumpstarts their heart post-hibernation remains unsolved. Ultimately, the wood frog survives unscathed, unlike any other animal.
https://www.nps.gov/gaar/learn/nature/wood-frog-page-2.htm