Shadowfern

This black moss is commonly found growing in small clumps On rotten logs, In marshes, and In damp forests.
It is small, growing up to 3 inches (8 cm) tall. It forms in thin clumps, and is overwhelmingly frail; it takes a lot of damage when trodden on.
When mature, emerald triangular capsules grow at the end of short, lime green sporophytes, eventually opening up during the late autumn to release thousands of spores.