Bone fragments.

Wood rots.

Leather dissolves.

The rare survival of organic material from this period is usually a function of specific extreme conditions: extreme aridity, as in the desert environments that preserved Egyptian mummies; extreme waterlogging in anaerobic conditions, as in the bogs of northern Europe that produced the famous bog bodies; or extreme cold, as in the permafrost environments of the Arctic.

What preserved Ötzi was the particular topography of the hollow in which he died.