Noun
The bony, cartilaginous, or other internal framework of an animal, as distinguished from the exoskeleton.
Source: Webster's dictionaryThe mesohyl functions as an endoskeleton in most sponges, and is the only skeleton in soft sponges that encrust hard surfaces such as rocks. Source: Internet
An endoskeleton is internal and present in all developed animals, as well as in many of those less developed. Source: Internet
The package for the T-800 Endoskeleton uses the cover of the movie poster for the artwork and reminds me a lot of the old VHS tape case. Source: Internet