What is a 'Kupamanduka' described in the ancient Sanskrit texts?

We can find a warning against isolationism in a parable about a well-frog- the ‘kupamanduka’- that persistently recurs in several old Sanskrit texts…The kupamanduka is a frog that lives its whole life within a well, knows nothing else, and is suspicious of everything outside it. It talks to no one, and argues with no one on anything. It merely harbours the deepest suspicion of the outside world. The scientific, cultural and economic history of the world would have been very limited indeed had we lived like well-frog