Reputed to be an aphrodisiac, this expensive delicacy is actually the cartilage of the shark's dorsal fin, pectoral fin and the lower portion of the tail fin. Though the fins of many shark species can be used, the soupfin shark is the one most broadly utilized for this purpose. Dried shark's fin can be found in Asian markets and is sold either whole or in shreds (sans skin and bones). The latter is more expensive because the labor-intensive work of removing the cartilage from the fin's framework is already done. Shark's fin cartilage provides a protein-rich gelatin that is used in Chinese cooking mainly to thicken soups-most notably, shark's fin soup.