Stockman pod's boxie form
The StockmanPod Suit is a robotic armored suit worn by the deranged scientist Baxter Stockman. It first appeared in the episode I Think His Name Is Baxter Stockman , and It's powered by Donatello's T-Pod. It was later upgraded into the Monster Of Doom.

It was later seen in The Pulverizer's flashback in "The Pulverizer".

Official Description

This madman contraption can turn any geek off the street into a serious bad guy