In the summer of 2006, I discovered these dried out and weirdly alien-looking Earthstar (Geastrum sp.) fungi under an oak tree in an oak-juniper woodland south of Tucson, Arizona.

An Earthstar, also known as an Earth Star Mushroom, splits open into numerous starlike rays when it rains, revealing its round, spore-filled inner sack and ejecting its spores into the wet environment.

Earthstars are saprotrophs and will grow and feed on decaying plant material, such as whatever these ones found under the oak tree.