Agar-Agar, a gelatin like substance is obtained commercially from the red algae, eg, Gelidium and gracilaria. It is used widely in preparing solid food media for the growth of bacteria or fungi in laboratory. An antibiotic chlorellin is obtained from Chlorella. It is also a good source of proteins and vitamins. It is also used in space travel as able to utilize all the CO2 released by the astronauts and provides O2 and food required by space travellers.