Board Thread:Theories and Rumors/@comment-30938718-20180803102949/@comment-34175192-20181003000848

Warptoad wrote:

I really don't get the confusion about Morro's age, Wu says the timeline of the flashback right at the beginning of it. "Soon after my brother went to train under Master Chen". Morro was a kid, and was younger than all of the Elemental Masters during the Serpentine War.

Wu and Garmadon are 200+ at the bare minimum. They could be anywhere from 200 to 999 Exactly. Morro probably died during the Hands of Time incident after the Serpentine War (assuming that it took him a while to find the Caves of Despair)

He was confirmed to be at least 14/15.