An Owon egg.
Owon eggs are a delicacy not to everybody's taste. They are characterized by a brown-purple shell and light yellow egg yolks.
In 2365 Commander Riker purchased some Owon eggs on Starbase 73 and used them to prepare an omelet. He invited Doctor Pulaski, Lieutenant Worf, Lieutenant Commander Data and Lieutenant La Forge over for for dinner, but only Worf enjoyed the eggs, which he called "delicious"; the others were unable to eat the meal because of their apparently bad taste. (TNG: "Time Squared")