why kids are so fascinated by this, why they are so gung-ho to eat hard-boiled eggs...when this object is on the table?
Think about it: it's a knife of sorts. As Wikipedia explains: An egg slicer is a food preparation utensil used to slice peeled, hard-boiled eggs quickly and evenly. An egg slicer consists of a slotted dish for holding the egg and a hinged plate of wires or blades that can be closed to slice.
My kids -- and their friends -- get very excited when I offer them hard boiled eggs. The "oohs & ahhs" are audible when the egg slicer accompanies the bowl of cooked eggs to the table. They argue about who will be the first to use the slicer, which way they should position the egg in the slicer, if they should double-slice the eggs to make them really small pieces, ie. messy crumbs aka prelude to egg salad.
I haven't yet shared a secret about the egg slicer with my kids and their friends: it can also be used for mushrooms! Shh...don't spill the beans, um, I mean the egg, um I mean the mushrooms.