Fancy Eggs only appeared in the episode Rule of Dumb and What Ever Happened to SpongeBob?. They are metal eggs decorated very fancily with gold, silver, and/or diamonds. Squidward has a collection of these eggs, he said so in What Ever Happened to SpongeBob?.
 Fancy Jewlery Egg
A Fancy Jewlery Egg just appears in the Episode What Ever Happened to SpongeBob?. It is the last known egg that isn't in Squidward's egg collection.
After Squidward destroys the Sponge-Tracker, Mr. Krabs orders him to help Sandy and Patrick look for SpongeBob. But when Squidward doesn't want to do so, Mr. Krabs gets a Jewlery Egg from his pocket and Squidward said that it's the last known jewlery egg that he doesn't have in his egg collection. They find SpongeBob and when he goes back out of the Krusty Krab, Squidward slips on grease on a Spatula. The jewlery egg falls out of his hand and lands on SpongeBob, destroying the egg.
On a Jewlery Egg you can see red jewlery and green diamonds. To Squidward it is a very special object.
 Fancy Egg Display
The Fancy Egg Display just appears in the Episode Rule of Dumb. In his house beside his swimming pool in Starfish form, "King Patrick" wanted to put a giant flat-screen television either on the wall or over the fancy egg display.
Patrick: (slurping a drink and reading a magazine) I need your opinion on something. Do you think... (two repo men are holding a giant flat-screen TV) the giant flat-screen TV should go... (camera pans to a fancy egg display) over the fancy egg display... (camera pans to a starfish-shaped swimming pool) ...or the indoor swimming pool? (bubble-wipe to Squidward sleeping. He wakes up to birds chirping and the sun shining)