A Taspar egg.
A live Taspar inside of its egg.
Taspar eggs originated from a local Cardassian creature called a taspar. Taspar eggs can be eaten boiled or raw. Most Cardassians are revolted by the sight of live taspar; it has a brownish color and a gelatinous consistency.
As a starving homeless child, Madred scavenged for and ate raw taspar eggs straight from the shell. In 2369, Gul Madred served a raw taspar egg in a similar manner to a captive Captain Jean-Luc Picard in an effort to degrade him. (TNG: "Chain of Command, Part II")