Why is this the answer?

The answer is snake because this clever riddle uses many fun word pictures to describe this long, amazing reptile. Let us look closely at each part of the riddle to see how the clues fit the answer perfectly. First, the riddle says, "I can sizzle like bacon, I am made with an egg." Think about the sounds a snake makes. When a snake is startled or trying to warn you, it makes a quick, dry hiss. That noise can sound a lot like a piece of bacon sizzling in a pan! Also, many snakes hatch out of eggs that their mother lays. So, the riddle is right that it is "made with an egg." Second, the riddle gives us a big clue about the snake's skeleton and movement: "I have plenty of backbone, but lack a good leg." If you look at an X-ray of a snake, you would see a very long spine with hundreds of tiny ribs. This long spine is its backbone, and it needs a lot of it to move. But snakes are special because they do not have any legs, so they are always wiggling and slithering along the ground instead of walking. Third, we read, "I peel layers like onions, but still remain whole." This clue is about how a snake's skin works. Since their skin does not stretch forever as they grow, snakes have to shed their old skin many times a year. The old skin comes off in one big, thin piece, like peeling a layer off an onion. When the old skin is peeled away, the snake underneath is exactly the same, healthy and whole, with new, brightly colored skin. Finally, the last part says, "I can be long, like a flagpole, yet fit in a hole." Snakes can be incredibly long when they are stretched out straight, like a tall flagpole standing up. But they are also experts at curling up tightly. When a snake is ready to go to sleep or hide from danger, it can coil its long body into a small, tight ball and fit perfectly inside a little den or hole in the ground. Every single part of this wonderful puzzle points right to a snake.