Replacing the defended sea rupee is a global myriad of, well, rupees. These glittering crystals can be found on the ocean floor along coasts, seas, and even deeper into the twilight zone, where they can either carpet the ground like grass or grow in periodic clumps depending on the available space and nutrients. They are mixotrophs which act a little like plants and a little like fungi; polar and deeper-living species where there is less light all or some of the time rely more on their ability to live off of detritus than on their photosynthesis, but all species do both to at least some extent.
Polar species, to deal with frigid temperatures, typically have darker pigment and thicker chitin layers in their crystal-like shells. This helps to protect them from freezing internally if they are unlucky enough to become locked in ice. These species may also have bulkier shapes overall for much the same reason, and they switch to a red pigment over the dark winters. Some polar species include R. darwinius (Darwin Polar Coast), R. fermiensis (Fermi Polar Coast), R. draconus (Drake Polar Coast), and R. hydrothalassus (Hydro-Barlowe Polar Sea), which all convergently share similar traits.
Individuals of any species living in the deeper parts of the twilight zone use red pigment instead of green, like many other crystals living in dimmer lighting conditions. The genus as a whole is generally very shade-tolerant due to being mixotrophs.
Sea rupees have an ancestral immune system of sorts. They have special proteins that identify foreign material and shred it, which protects them from many parasites and pathogens. They avoid shredding their own cells or organelles using individual-specific mineral markers, similar to markers used by many earth species for the same purpose.
Like all aquatic crystal flora, sea rupees reproduce sexually using water-borne spores. Species in regions with lots of competition for ground space may have hardier spores designed to degrade more slowly, while those in areas with less competition typically have shorter-lived spores.
Species not mentioned above:
- R. rupeemimus (LadyM Twilight Slope, LadyM Twilight Floor, Barlowe Temperate Coast, East Darwin Temperate Coast, East Glicker Tropical Coast), a typical sea rupee
- R. circumferi (LadyM Twilight Slope, LadyM Twilight Floor, Vailnoff Twilight Slope, Vailnoff Twilight Floor, Dixon Tropical Coast, Wright Temperate Coast, Dixon-Fermi Temperate Sea, Wright-Orpington Tropical Sea, Drake-Orpington Temperate Sea), another typical sea rupee with relatively short-lived spores
- R. kyrtoepizon (Vailnoff Twilight Slope, Vailnoff Twilight Floor, West Darwin Temperate Coast, West Glicker Tropical Coast, Hydro Tropical Coast, Hydro Temperate Coast, Hydro-Barlowe Temperate Sea), an unusual sea rupee which has a darker coloration like a polar species despite living in temperate and tropical waters.