Ulva lactuca is a thin green algae from the Chlorophyte division, with a worldwide distribution, usually found on rocky substrates and is commonly referred to as "Sea lettuce" for resembling common lettuce. It has a slimy texture, a green to dark green color and its stalk is flat with a smooth surface. This algae can reach up to 18 cm in length and 30 cm across, often with a torn and ruffled margin.