When you are young with a shell and you are growing very fast, life brings new surprises every day.
For example, perhaps yesterday you maneuvered your strong young shelled self into your favorite parking spot right under the shiny desk chair. Then, when you were ready to get going again, you simply hoisted yourself up and walked away.
So today you see that your same favorite parking spot is free and you head right for it. You position yourself just-so and begin to pull into it.
But something is blocking you from maneuvering in the direction you need to go. You move this way, that way, you try backing in, going sideways….no luck.
Whatever could be causing the problem? Yesterday you fit just fine!