Barometer Earthstar (Astraeus hygrometricus). An interesting little mushroom. Starting out as a minuscule, round, white blob that looks like the mushroom that I wrote about 2 days ago, a very small Giant Puffball Mushroom.

As it matures it takes on the shape that it is known for, with 4 to 20 irregularly sized petals or rays, reaching a diameter of 1/2 to 3 inches across. As the petals open, a round spore case is revealed at the center.

The petals respond to humidity in the air, opening when the air is moist, and slowly closing when the air is dry. Dispersing spores when there is high humidity.

Amazing.