The Nightmare Womb has a chance to drop a special item, if you can kill it before it gives birth. The items include formulas and a special ingredient called a Mother's Heart. Like the Flesh Sac Items these formulas do not need a building or research to complete the item, only the items need to meet the formula.
Crafted Items Edit
All three of the orbs created give a +% to your building that you put them into.