All penguins in Club Penguin have ID numbers, such as P103223183 or P169314173. The ID number signifies how old a penguin is in Club Penguin. For example, if a penguin's ID was P145965716 then they would be the 145965716th penguin created on Club Penguin.
The earliest known penguins are caveguins, also known as cave penguins. They lived in the prehistoric era of the Club Penguin Island with dinosaurs. There, they worked, lived, and played. The caveguins had a more limited vocabulary than the present-day penguins. Due to the Prehistoric Party 2013, many caveguins were confused about penguins coming from the 'strange shiny thing', known as the Time Trekker. They then discovered that they were from the present. The only named caveguins are Garugg the Ugg Ugg and Dugglus. They also used slang.