A grain deformity caused by stress. This one was 33 cm wide and a meter above the ground. Much darker than the tree bark with a bumpy surface.
Spotted at the Garvan Woodland Gardens in a mixed forest.
Burls yield a very peculiar and highly figured wood, prized for its beauty and rarity. It is sought after by furniture makers, artists, and wood sculptors. There are a number of well-known types of burls (each from a particular species); these are highly valued and sliced into veneers for furniture, inlay in doors, picture frames, household objects, automobile interior paneling and trim, musical instruments, and woodturning. (Wikipedia)