Threitol

Threitol is a four-carbon sugar alcohol with the molecular formula C4H10O4. It is primarily used as an intermediate in the chemical synthesis of other compounds. It is the diastereomer of erythritol.
In living things, threitol is found in the edible fungus "Armillaria mellea".
It serves as a cryoprotectant (antifreeze agent) in the Alaskan beetle "Upis ceramboides".