The Gourm-Egg (also known as the Long Egg) is a 30cm long, 500 gram hard boiled egg that is used by airlines, hospitals and other establishments that feed many people. It is impractical for quantity meal servers to boil several hundred eggs, so Gourm-Eggs are used instead. A single Gourm-Egg can yield at least 75 slices of egg.
The Gourm-Egg was invented in 1968 by Purina Ralston. It is classified as an "extruded product" because the yolk is cooked first and then extruded to be the diameter of a normal egg yolk. The cooked yolk is then covered in egg white, with the yolk placed slightly off-centre to prevent the egg slices from looking too perfect. A small quantity of starch or food gum is added to prevent the egg toughening during the freezing process.
Gourm-Egg slices look very authentic, and the only way to tell them apart from a normal egg is by looking for small wrinkles at the edges of the egg slice. These wrinkles are caused by the plastic wrapping tube.
Reference: Q & A with Dr. K , Dr. Karl S. Kruszelnicki. HarperCollins 2001