Phobos is the arch-nemesis and re-colored variant of Biotron. Works just like his blue and white counter part, walking on his feet, or rolling along like a tank on treads on his back. His chest cavity can hold a Time Traveler or other Micronaut figure. I actually prefer the coloring of Phobos over Biotron, but that head is just goofy looking. Fortunately you can reverse it and get a more menacing look. Phobos is one of the more surprisingly difficult items to acquire in the Mego Micronauts line, especially in good condition. It took me three years to get one.