not on poptropica
its in the museum on mainstreet of steamworks island :)
There are solutions at the related questions below. (You win by assembling a Mech walker and defeating monster plants. When you have earned the Island Medallion, you can leave Steamworks by using the doorway which is one level above the dead-end basement in the storeroom.)
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
steamworks island
There is a video walkthrough at the related link below. There are written WikiAnswers solutions at the related questions, as there are for all Poptropica islands. (How do you beat Steamworks Island) (What is the walkthrough for Steamworks Island)
Steamworks island
how to do the bridge terminal on poptropica's steamworks island
you can get it on the far left of steamworks island, past the living headquarters.
jump