Puffball (Basidiomycota)
White, spike-covered puffball mushroom in wet leaves
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There are quite a few varieties of puffball mushroom, all belonging to the division Basidiomycota and having their own unique characteristics. A quirky trait they all share is that they do not grow an open cap with spore-bearing gills; instead, the spores are grown internally and the mushroom develops an aperture or splits open to release the spores. Besides their general appearance—similar to a plain old white button mushroom, but often much larger and sometimes covered in hairlike spines—they're called puffballs because clouds of spores "puff" out when they burst open or are hit with, say, falling raindrops.