What are the flattened cells important in protection that fit together like tiles?

Answer 1

Well, there lots of shapes, but three common forms are cuboidal shaped cells (which are like cubes), squamous cells (which are like cuboidal except flattened), and then there are columnar cells (which are shaped like columns).

As for the flattened cells that are important for protection, this is clearly referring to squamous epithelial cells. Every lumen of our bodies has a layer of epithelium surrounding it, partly for protection. The cells of these layers can be a variety of shapes, but squamous is common. Skin, for example, is squamous epithelial tissue. And yes, these cells fit together like tiles, so their shape is very important to the barrier function they serve. Epithelial cells can form different kinds of junctions between each other. One type, called a 'tight junction', causes the cells to bind to each other extremely closely.