Cell membrane – (also called the plasma membrane, plasmalemma or "phospholipid bilayer") is a semipermeable lipid bilayer found in all cells; it contains a wide array of functional macromolecules. Cell wall – A fairly rigid layer surrounding a cell, located external to the cell membrane, which provides the cell with structural support, protection, and acts as a filtering mechanism. Centriole – A barrel shaped microtubule structure found in most eukaryotic cells other than those of plants and fungi.