Is a tree a shell structure?

FRAME STRUCTURES

Frame structures are structures that are made up of rigid (stiff, firm, difficult to bend) parts joined together to form something called a framework. These parts are known as members. There are lots of examples of frame structures such as a bridge - a bridge is a frame structure that spans a gap, and a bicycle is a frame structure that supports a load such as the mass of a person.

SHELL STRUCTURES

Shell structures contain or protect things from the outside and are usually hollow inside. In a shell structure, the outside layer of the structure holds the whole object together. Examples of shell structures are the mug that holds your coffee, the snail shell which both protects and contains the snail, honeycomb which contains and protects bee's honey and shells of nuts.