Mushroom more or less shaped like an upside-down pear, about one half to an inch wide. Pale brown when young, turning a darker brown. When young studded with tiny spines that soon drop. Becomes a sac filled with spores. When the spores mature the sac develops a slit at the top and the spores are expelled when wind, animals, or rain disturb the sac. Occurs singly or more usually in crowded clusters on decaying wood of logs and branches.

A common fungus throughout North America. Common in Wildwood in areas with abundant fallen wood..

The habit of growing on wood is the best clue. Gem-studded puffballs (Lycoperdon perlatum) grow on the ground, are white, and have prominent spines. Wolf's milk slime (Lycogala epidendrum -- a slime mold, not a puffball) is similar and also found on wood, but is much smaller and it starts pinkish, turning dark gray.