Witches Egg or Ravenel Stinkhorn volva

these are all pictures of the same species in different forms; this is the "egg" or volva - the immature fruiting body found underground; it is whitish or pinkish, egg-shaped, about 5 cm; it has a leathery outside skin (picture 3) that breaks open to reveal gelatinous material covering a brain-looking "egg (picture 2) that when split in half (picture 1) reveals the stinkhorn to be; stinks; The volva attaches to the substrate with whitish "rhizomorphs" which are thick, cord-like strands of mycelia (picture 5)