Earthstars start out as a round ball. When they are ripe the outer layers peel back and the inner chamber releases spores. After observing it for a couple of days, I realized that this was not an earthstar mushroom, but a false earthstar mushroom. I had not known false earthstars existed until I did a little online research trying to pin down exactly which earthstar it could be. I was a little crushed until I realized that false earthstars were even cooler then earthstars, and they became my new favorite mushroom.
What distinguishes the false earthstar from an earthstar? Well, mycologists separate them based on the thin chamber walls inside the area where the spores are developed, the nature of the split in the spore sac, the absence of sterile tissue at the base of the spore sac, and the size of the spores themselves.
Perhaps the easiest way to differentiate them (and what makes them so cool) is the hygroscopic properties of the outer 'sun-like' rays. This special property means that when moisture is present in the air, the rays absorb it and uncurl. This pushes the spore sac up in the air, so that spores are dispersed farther in the correct (moisture-rich) conditions. When the air is dry, the rays 'dry out' and curl up to protect the center of the spore sac. Few 'true' earthstars have this property. What a neat thing to find in my backyard!