Emerald Spore Moss

This yellow-green moss is commonly found growing in tiny clumps On rotten logs, In bogs, and On trees.
It is short, growing up to 3 inches (8 cm) tall. It forms in large clumps and they overwhelm an area rapidly, and is extremely light.
When mature, emerald crescent-shaped capsules grow at the end of short, lime green sporophytes, eventually opening up during the early summer to release dozens of spores; it can cause severe allergic reactions.