Cytochrome

 is a Tier 4 Tank that upgrades from Mitochondrion at level 45.

Design
The looks identical to the Mitochondrion but with an additional, even smaller barrel added to its existing stack. All of the barrels but the main one are widened very slightly to accommodate for it.

Trivia

 * Like the Mitochondrion, this tank is named after a biological component, specifically a type of protein.