Hamashirama are bizarre-looking, aquatic swimming creatures. They are widespread in the floating sea of the 5th layer. They are said to eat sedimentary life. Their appearance outside of the water is vastly different to the form they take when swimming, which somewhat resembles an air balloon. Much like all the aquatic creatures of the 5th layer, they're unaffected by the curse because they have a different set of sensory organs than surface organisms.
Their anatomy is quite strange. All their internal organs are packed into their head, and they spray a mucous produced by their organs through spitting from their mouth. This mucous has paralyzing properties and is used to stop the movement of predators. In some reports, they have been seen using other paralyzed creatures as living shields. Outside of the water they die very quickly and don't possess any form of notable offensive capabilities, thus making fishing for them harmless. Trying to catch one in water is more difficult, and the act of diving into the sea of the 5th layer is synonymous with suicide due to the sensory deprivation of the curse.
Hamashirama are edible and quite delicious. While their appearance is rather displeasing, they are described to be sweet and tasty. The best form of consumption of them is considered to be raw, much like how sushi is typically eaten. Their skin is very tough, so it can be used as a plate. The oily organs should be removed however, since they are poisonous.