When the Guyvers attacked Cloud-Gate, Chronos' Asian headquarters in Tokyo, they were briefly confronted with four Hyper-Zoanoids, presumably the designated armed guard for the location. Their specialized abilities proved woefully inadequate against the Gigantic Guyver, who blasted them all to smithereens with his gravity cannon.
Billbo-Negg, the heaviest single Zoanoid on record (only the combined form of the Branchai brothers is heavier) was practically a ball of armor; his body structure was not dissimilar to a stocky, humanoid tortoise with a disproportionately large shell. He could withdraw most of his body inside his shell (although more like an armadillo than a tortoise, really), forming a rough, spiked ball that was virtually indestructible. By altering the fluid distribution inside his body, he could still move in this form, rolling around like a giant, death-dealing bowling ball.
Another Hyper-Zoanoid, which appeared identical, showed up right after Powered Zerbebuth's confrontation with Guyver II-F - and in an ironic repetition, was destroyed before being able to show what it could do, this time by Richard Guyot.