The lorica can be distinguished between different species by the orientation of spines or other ornamentations, such as pores, warts or ridges, and can range from being colourless to orange/brown or even black based on the nutrients in their surroundings. Euglenoids have not been observed to undergo sexual reproduction; however, asexual reproduction does occur through mitosis followed by cytokinesis. The formation of the lorica after asexual reproduction first occurs through the external skin and then a fibrillar layer is formed between the cell surface and the skin. Then manganese and ferric hydroxide compounds are precipitated on the inner fibrillar layer to produce a thick envelope and the original external skin is lost. However, differences in these processes exist among species.