They may appear as plant-like beings and share some key elements from their tree (the colors and textures, for example). Sometimes they appear as ghost-like Humans as well.
They will protect the home of anyone who worships them, but beware anyone who might try to cut their tree down...
It is believed to live, or be the spirit, of a tree. Not all trees have Kodama dwelling in them, however, and usually these entitites tend to inhabit trees of very great age or size. It is said a person who cuts down a tree with a ko-dama living in it will bring calamity upon their entire village, and often the sacred rope called shimenawa is wound around trunks thought to contain these spirits in order to protect them.
While ko-dama are generally invisible to human eyes, they are thought to mischievously play with and mimic human voices, creating echos in the forest. "Echo" has also come to be another meaning of the word kodama. It is said that the sound of a falling tree is the last cry of a Kodama.