Caviar.

Caviar are the black eggs of the sturgeon fish, known to be extremely expensive and hard to get.  The best come from Russia, but as the species is endangered, the primary source now is American captivity.  You can tell them apart from other fish eggs because of their black color: most other eggs are red.

The sturgeon fish, the source of caviar, was supposed to be extinct for millions of years during much of the 1900s, but they sighted a sturgeon off the coast of South Africa in the second part of the century.  All scientists were astounded when they found that the fish had been alive and well.  In fact, everyone was surprised except the local South African fishermen who had been catching the fish all the while.  Caviar is normally served on a piece of bread at the fanciest parties, and is a delicacy with fishy flavor that is strange and yummy.