Ribosomes are one of the very few organelles that are not bound by a membrane, hence they are called membrane-less organelles. Ribosomes are small, non-membranous organelles present in both eukaryotes and prokaryotes. They may be found unattached and floating freely in the cytosol or attached to the outer surface of the rough endoplasmic reticulum. The lack of a membrane is a notable feature of ribosomes. Ribosomes are significant sites of protein synthesis. Transporting proteins into a membrane-bound protein is energy-consuming. The absence of a membrane facilitates the easy transportation of proteins without consuming a lot of energy.