They can be further classified into different subspecies, including Rock Humans (岩人間 Iwa-Ningen), Rock Animals (岩動物 Iwa-Dōbutsu), and Rock Insects (岩昆虫 Iwa-Konchū).
Life cells that bonded from silicon were born at the same time as carbon-based cells. While these cells were few in number, the bodies that are formed by these cells are known as Rock Organisms. It is unknown why life diverged into those two paths. However, it could be that Rock Organisms were created as a fallback in case carbon-based life reached a dead end.
The Rock Human subspecies eats plants, fruits, nuts, meat, fish, and all other forms of life. They enjoy honey, and all are allergic to mangoes. When a Rock Organism dies, it leaves no corpse, as it crumbles away into rocks.
Rock Skin: Each Rock Organism has the ability to shift their outer appearance into a rock-like state and vice versa at will. In their rock form, they are able to camouflage into their surroundings, and improve their durability to some extent. When they do, most of their actions as a living being come to a halt and they can endure high temperatures or a lack of hydration.
Stands: 95% of Rock Humans possess Stands. The reason for the high proportion of Stand users in their population is likely due to them living in "special places" including the Devil's Palm and near the Wall Eyes in Morioh, which are locations known for being able to grant Stand abilities. Rock Animals and Rock Insects have unique abilities but they do not appear to be Stands.
Intangibility: Most Rock Animals and Rock Insects seem to be capable of intangibility to some degree. Iwasuke can phase through walls, Doremifasolati Do can phase through the ground, and Dododo De Dadada can phase through the ground as well as other objects.
- Main article: Rock Humans
Rock Humans are the primary antagonistic force of JoJolion. Visually, they appear no differently than humans and can also procreate much like them. However, their behaviors after childbirth are a lot different and they have long hibernation habits. Rock Humans are fundamentally independent and some act as parasites within human society.
Little is known of Rock Animals, but they are comfortable being pets and subservient to their owners. While most of them have served as minions of the Rock Humans, it is shown that they are capable of living in harmony with humans. Iwasuke is listed as a further classification of a Rock Animal, stated to be a Rock Dog (岩犬 Iwa Inu). Interestingly, most Rock Animals' names, including Rock Insects', contain vocables, as per the songs they reference.
Rock Insects are a subspecies of Rock Animal that, unlike Rock Humans, have noticeably different anatomy compared to their carbon-based counterparts. They also differ from Rock Humans in that they have managed to largely avoid contact with humans, and remain largely undiscovered. Some of them can be carnivorous.