Frame structures can be as simple as a garden fence or something much more complex such as a skyscraper. A shell structure has a thin curved outer layer and is hollow. These structures often are ...

That's where the shell's structure comes in ... no matter how fierce they may be. Turtles are amazing. EDITOR'S NOTE: This video was originally published in July 2019.

There’s another way of making a structure. A shell structure is just made of a thin, curved outer layer and it’s hollow inside. Like this, or this, or this, or this. A shell structure doesn ...