The EGG file extension is related to the Panda3D a 3D game engine. The *.egg file stores transform definition data.
EGG file extension - Panda3D transform definition file
What is egg file? How to open egg files?
File type specification:
The EGG file extension is related to Panda3D, a 3D game engine: a library of subroutines for 3D rendering and game development. Game development with Panda3D usually consists of writing a Python or C++ program that controls the Panda3D library. Panda3D originated at Disney, and is still being used for their commercial games. Pirates is the most recent addition to their lineup of games based on Panda3D.