Burrowing detonator
A burrowing detonator was a type of mobile mine.
A burrowing detonator was an oblong hemisphere, segmented and flexible like an insect, equipped with claws for digging. When activated, they would burrow into the ground, moving about and seeking targets - though only within a certain radius of where they had been activated. Moving about with enough speed as to be difficult to dodge, they detonated with a powerful explosion that left a mildly poisonous chemical residue behind.
Devices of this type were used to great effect on Anobis during its civil war.