👉 A tuboid is a type of muscle that is primarily composed of red blood cells. Tuboids are found in the heart, lungs, and liver. They provide oxygen to the body's tissues, but they also contribute to waste removal by pumping out carbon dioxide through their veins. Tuboids can be divided into two types: muscular tuboids (also known as fibrous tuboids) and non-muscular tuboids (also known as cardiac tuboids). Tuboids are responsible for approximately