The Super large egg is an item that respawns at the Fred the Farmer's house chicken yard in Lumbridge. It is on the floor, but players cannot pick it up if they aren't doing the quest Cook's Assistant, even with Telekinetic Grab. If a player tries, they will receive the message, "You have no reason to pick that egg up; eggs of that size are only useful for royal cakes." The egg may also be obtained by killing a chicken (only if you are doing Cook's Assistant).
Its right-click option has a symbol next to it that appears to be a chef hat, because it is used in the Cook's Assistantquest.