Cursed Objects
Items carrying enough cursed energy and enough history to be dangerous on their own. Most are the remains of dead sorcerers, and the strong ones can be incarnated into a living body.
Cursed Womb: Death Painting
Nine objects made from the mixed blood of a cursed spirit and a human woman, the result of Noritoshi Kamo's experiments. Three of them hatched into Choso, Eso and Kechizu.
Prison Realm
A special grade object holding a barrier that seals anything put inside it, with no way out from either side. It is the only reason the Shibuya Incident worked, and Gojo spent the rest of the arc in it.
Ryomen Sukuna's Fingers
Twenty fingers, each a special grade cursed object, holding what was left of Sukuna after his death. Kenjaku scattered them, and eating one is how the series starts.