Keys Mud is high in minerals and trace minerals essential for feeding sea grasses, macro algae, as well as stony corals. This "Keys Mud" comes directly from the Florida Keys and is made up of high amounts of calcium carbonate.   It is grey in color and  both very fine and gritty due to various stages of decomposition of materials (such as halimeda).  It contains beneficial bacteria and tiny worms and therefore great for seeding new tanks, refugiums, or just boosting your current system.  We have collected this mud and have kept it oxygenated since its exit from the ocean. This recent collection contains MOSTLY Halimeda leaves in various stages of decomposition. This makes this "mud" Very coarse and virtually Halimeda Leaf Litter. Although there is still a lot of fine "mud" in each cup.