The presence of different forms of RuBisCo in microalgae is influenced by their evolutionary lineage and physiological adaptations, making it important to ask more specific questions about particular microalgal groups. For instance, diatoms, a diverse group of microalgae, possess Form I C/D Rubiscos, which are characterised by small subunits with a short βA-βB loop and a carboxy-terminal extension forming a β-hairpin structure (βE-βF loop).