Thornstack

The Thornstack replaced its ancestor in the southmost waterways of Darwin. The number of mounds it grows in a lifetime has more than doubled, which has doubled the organism's size. The mounds grow at irregular rates (resulting from enviromental factors), giving the stacks a slight lopsided look. The base "leaves" have a wider base to support each stack; the mounds are also denser near the bottom to aid in this. As it grows, the black photosynthesizing pigment wears out, turning older mounds a chalky grey; this helps the organism dispel heat easier. Other than these changes, it is the same as its ancestor.