Brown Egg Blue Egg
Internal And False Layer
by Diana Hedrick
Information from Merck Vet Manual
January 2007
Here are several other articles about weird eggs. If your bird has laid one, it might be an isolated case or a sign of big trouble. For your bird's sake take the time to read these and understand.
Christmas Alien Egg
Penny's Surgery
Weird Eggs
Weird Eggs - Peter Brown
Just to clarify, an egg being caught/not laid and breaking inside causing septicemcia is different than an internal/false layer.

(See the Merck manual definition of Internal and False Layers below)

These conditions are often chronic and get only worse with time. They eventually lead to secondary peritonitis or ascites killing the bird.

Merck Vet Manual

Internal Layer

In these hens, partially or fully formed eggs are found in the abdominal cavity. Such eggs reach the cavity by reverse peristalsis of the oviduct. If they have no shell, they are often misshapen due to partial or complete absorption of the contents. Frequently, only empty shell membranes are present. No control or treatment is known. This condition is related to erratic ovulation and defective eggs (see Defective or Abnormal Eggs).

False Layer

These hens ovulate normally, but the yolk is dropped into the abdominal cavity rather than being collected by the oviduct because of obstruction of the oviduct after infection with E coli or Mycoplasma gallisepticum. The yolk is absorbed from the abdominal cavity. The hen looks like a normal layer but does not produce eggs. Hypoplasia of the ovary and oviduct has been associated with infectious bronchitis virus infections (see Infectious Bronchitis: Introduction) at an early age (1-2 wk). Atresia or even atrophy of the ovary are caused by severe stress, chronic infections, and feed refusal due to mycotoxins in the feed.

Hypoplasia: Underdevelopment or incomplete development of a tissue or organ.
Atresia: Absence of a normal opening or failure of a structure to be tubular.
Brown Egg Blue Egg