What is a gagu?

Here is what we know so far...

• Cannot be a full human inside of a costume. It has to be a puppet!
• Cannot be CGI! It must be hand-crafted — or at least look like it has been hand-crafted.
• Can be a puppet that looks like a human, but its gagu status must be confirmed.
• No muppet can be a gagu.
• Some objects with human traits can be gagus.
• Must communicate in a language of some kind. Not just meaningless growls or grunts.