Blighted Ovum

Blighted Ovum is a boss that can appear in Cellar.

Behavior[]

Blighted Ovum starts separated into two parts.

Suture is invincible and slowly floats towards Isaac, firing a horizontal Brimstone shot whenever Isaac is to its left or right. Suture can not be killed and will die once Contusion does.
Contusion constantly chases Isaac while leaving behind a trail of red creep, he periodically charges and gains speed. Unlike Gemini, he will not stop for a breath but slows down to his regular speed.

Blighted Ovum in-game.
Blighted Ovum as one of Delirium's forms.
Contusion's and Suture's appearance before Repentance.
Sketch of what appears to be an older concept of Blighted Ovum, along with other bosses that were to be added in the original The Binding of Isaac's Wrath of the Lamb DLC. Note that the behaviors mentioned in the concept art were never implemented in the original game onwards.

Blighted Ovum was added in the Wrath of the Lamb DLC for the original The Binding of Isaac.
It is the posthumous version of Gemini.
In medicine, a blighted ovum is a pregnancy in which the early pregnancy appears normal on an ultrasound scan, but later no visible embryo develops.
Blighted Ovum has skin on its body in the boss art, but it doesn't in-game.
Blighted Ovum is the only boss in chapter 1 that is a posthumous version of another boss.
- Gemini also shows up in chapter 1, which makes it one of only four bosses to have its posthumous version in the same chapter, the other cases being Polycephalus and Chub having The Stain and Carrion Queen, respectively, in chapter 2; and Tuff Twins having The Shell in Chapter 2.5.
  - However, Blighted Ovum doesn't appear in the same environment as Gemini who appears in Basement, while Blighted Ovum appears in Cellar.
If encountered in a Double Trouble boss fight, its Brimstone laser can damage the other boss.
In Wrath of The Lamb, when Blighted Ovum was killed Contusion would shoot 8 extremely fast tears in the cardinal and ordinal directions, and after a short delay would be followed up by Suture who would explode similarly.
In the Bestiary, Suture is referred to as "The Blighted Ovum Baby".
Blighted Ovum, Big Horn, Triachnid, and ??? (Boss) are the only bosses whose portraits were completely changed in Repentance (beyond simply adding more detail). Of these, only Triachnid, Isaac, and ??? didn't receive new sprites.