Wood

Wood is a by product of trees. It is mostly made up of water, cellulose and lignun. Water and cellulose are the soft squidgy bits, whilst lignun is the hard bit. If you hit a tree whilst in possession of a reasonable amount of kinetic energy it is the lignun that causes the injury, not the water or the cellulose.

Wood is very useful, as it is combustible, good for construction and comparing relative displacement in witch trials.