Top 10 unbelievable historical concurrencies. Caviar is an expensive delicacy consisting of the unfertilized eggs (roe) of sturgeon brined with a salt solution. Classic caviar comes primarily from Iran or Russia, harvested by commercial fishermen working in the Caspian Sea. A specific species of sturgeon called beluga provide what many consider to be the best in the world. A female sturgeon's roe supply may constitute as much as 25% of her total body weight. Considering that mature sturgeons can weigh 300 pounds, each one can provide a substantial amount of caviar over a lifetime.