elasmobranch: any of numerous fishes of the class Chondrichthyes characterized by a cartilaginous skeleton and placoid scales: sharks; rays; skates
cartilaginous fish: fishes in which the skeleton may be calcified but not ossified
spanish bayonet: a stiff yucca with a short trunk; found in the southern United States and tropical America; has rigid spine-tipped leaves and clusters of white flowers