(Difficult Question) What is Gunter's possible AGE?

well the average lifespan of a penguin is... about 15-20 years... so... anywhere younger than that... it takes about 3 years for a penguin to fully mature (so that it can reproduce). and they don't begin breeding until somewhere between 4-6 years old (depending on the penguin species)

so it's older than 3 and younger than 20... ~logic

Probably as old as the Ice King....lol xD