Cursed Womb

A Curse Womb (呪胎戴天) refers to the uterus-like apparition that grows a Curse within it that will grow and be released.

Description
Curse Wombs that grow and change shape are expected to produce Special Grade Curse Spirits. A Curse Womb can be created from a powerful Cursed Object such as one of Sukuna's fingers. It attracts other Curses in the area and after gathering enough Cursed Energy, the Curse Womb gives birth to a Special Grade Curse embued with the strength of the Cursed Object used to create it.

Death Painting
A Cursed Womb: Death Painting, or Cursed Death Painting Womb, (Kusouzu) is a type of Cursed Womb that is half-human, half Cursed Spirit. It is unclear how they are formed precisely. In the Meiji era, Noritoshi Kamo succeeded in creating three different death painting wombs in the form of aborted fetuses when he discovered a girl who could give birth to children who were half curse.