Scisers were clawed aquatic predators indigenous to the planet Zebes' subterranean lakes of Maridia. They superficially resemble crabs.
Several were brought aboard the Biologic Space Laboratory Research Station where they were placed within Sectors 1 & 4, where they were subsequently infected like nearly everything else by the X Parasites. Sciser-X are improved upon by allowing them to fire spheres of energy from their open claws. Because of this, their claws now faced outwards instead of inwards.
As both Zebes and the BSL have been destroyed, and no other havens for them have yet to be discovered, Scisers are considered to now be officially extinct.