Boneweed

Boneweeds are more adapted to life on land than their ancestors. Unlike their ancestors, boneweeds live in the supralittoral zone, and as such are only submerged during high storms. However, they still require plenty of water. Boneweeds require calcium to build their exoskeleton trunks, but are no longer able to absorb calcium from seawater. They must instead absorb calcium from the sand, which usually means they are dependent on the calcium-rich remains of other bonephyta species. However, if calcium-rich sand is eroded from a nearby calcite or dolomite formation, previous bonephyta colonization is not needed.

The photosynthetic "shells" of a boneweed—now called mups—have 25% less calcium compared to the "shells" of their ancestor. This functions as a calcium-saving measure, allowing it to concentrate calcium in its trunk. The nodes of the trunk have small interior spaces filled with delicate living tissue, much like spinal cords inside spinal cavities. The delicate tissue functions like a phloem and transports water and nutrients to and from the mups and roots. Boneweeds' roots are primitive: they are essentially miniaturized photosynthetic mups with little calcium that grow in tufts around the base of the trunk.

Pollen-like spores ("spollen") grow on the undersides of the upper mup halves. When mature, the spollen easily detaches and is carried by the wind. If the spollen grains land on the inner side of other boneweed mups, they will be fused with the individual's own spores to create a new, larger spore, which can germinate to make another boneweed individual. Boneweeds tend to grow in clusters.