The Metal Dragon and its hybrids become available at Level 17.
A fairly new addition to the list of dragons, metal dragons usually generate relatively little income but their habitats can store a lot of income over time, allowing easier wealth accumulation. They are also a great way to quickly gain experience in Dragonvale. The Metal Dragon's hybrids sell for a lot of money, providing an alternative way to earn extra cash.
"For years explorers were afraid to enter the Tull Caverns because of the loud noises that could be heard coming from deep below. It's only thanks to the brave Dickinson Osborne that we now know that these sounds come from the metal dragon's unique behavior of 'drumming' precious metals with their heavy tails."