On moist areas of our glade after a rain we come across these piles in the trails. It looks nasty, a cross between rock snot and rotting moss. It is actually a cyanobacteria called Nostoc. They grow in chains or filaments covered with a gelatinous sheath. They have photosynthetic pigments which accounts for the green color.
Since it is invisible until rain causes it to blossom, it had a rich folk lore history. It was assumed to fall from the sky with the rain, getting it named Star Jelly or Witches' Jelly.
