A cable mole? Havent seen one like that before, looks like its designed with a specific purpose. Like running cables through a woodland where you would have to cut through roots?
It looks like what he says it is a cable plow. However the only ones I've ever seen used where mounted on D6 or D7 Cats and 6' to 8' tall. They use them to lay lines and fiber optic cable.
I saw one of these units in operation. Pretty slick. The local telephone company had to replace my underground phone line and they used a small walk behind power unit the actualy oscilated the blade through the ground. They tied the phone wire to the end and just started the cutter and walked to the house with it. When I saw it, it did have serrated teeth to cut through roots. This unit went down about 16".