Le caviar d'escargot means snails' eggs. They look like white pearls and are sprinkled raw on other foods.  It is a very expensive food, costing around 1,700 euros per kilo. 

Specialist snail breeders collect the precious eggs by hand.  A snail breeder is known as un héliciculteur.  Interestingly, the snail mucus is also collected to use in some anti-ageing creams.