This image of a knotted protein comes from a microorganism called methanobacterium thermoautotrophicum that breaks down waste products and produces methane gas. This was the first structure of the most ancient type of single-celled organism -- archaebacterium. Protein-folding theory previously held that forming a knot was beyond the ability of a protein; as technology improves, biologists are determining higher-quality images of structures. Researchers used the powerful X-rays at the Advanced Photon Source at Argonne to determine the protein's structure.