Like the Escarghoul, the first Zombster was an isolated, freak mutation created when a normal zombie accidentally absorbed an organism lurking within its body, in this case, a scavenging crustacean. Since then, the creatures have multiplied, their bite infecting humans with a variation of the zombie virus that will ultimately transform them into Zombster themselves. Fortunately for zombiekind, this is a rare occurance, as these large, strong and thickly armored monsters very rarely leave enough of their prey behind to undergo this slow metamorphosis.

   Like a hermit crab, the Zombster is compelled to find a "shell" for its fragile tail, but few things can accommodate its size. Hollow logs, discarded crates and the skulls of immense monsters have all been observed in use as a Zombster's mobile home, but there appears to be a notable preference for caskets; probably because they inevitably turn up in this powerful burrower's search for carrion.

   When two Zombster meet, they join their claws and attempt to dismember one another. The loser is mostly devoured, but its zombie aspect will regenerate its body in time.