Gracilaria gracilis belongs to the red group of algae. Its tone varies between purple and greenish colours . It is a cartilaginous and cylindrical  algae, with branching very irregular and slim (2mm diameter). It can reach up to 50 to 60 of length. Their internal tissue is formed by big cells with thin lightly colourless walls and with small coloured cells in outer cortical zone. This algae is used in agar extraction.