Possible Clues:

• Like prickly pears
• No space for regular shape
• Like an eggplant
• Elliptical ring, useless
• Duck fines free area at Humpty Dumpty¿s space
• Egg-shaped or round hole
• Shaped like a common breakfast item
• Duck sits on empty space — or on something that's this?
• Ordinary space is egg-shaped
• Like an egg that's old and useless