it's across the drawbridge
on the top right when you enter the island
its in the museum on mainstreet of steamworks island :)
The monsters on Steamworks are all mutations of plants on the island. They took over the island after being altered in the Research labs (Production Zone) to the right of the Hub. You battle them at several locations on the island. (see related question)
SPOILER WARNING: The citizens of Steamworks Island had to hide from the plant monsters that they created so they hid themselves in a hibernation area for 200 years.
if you go to the right you will see a place to put the dirty beaker
you break it with your rubber mallet.
It's Steamworks Island #14th Island
(The solution is at the related question "How do you beat Steamworks Island")
the crab on steamworks island is next to the living quarters
You go to Steamworks and head to the museum and there is the Deogen
SPOILER WARNING: The citizens of Steamworks Island had to hide from the plant monsters that they created so they hid themselves in a hibernation area for 200 years. The path to their chamber is through the plant-covered annex at the far left of the Living Quarters area.
steamworks island