Description: A young thallus starts out as a sac and as it matures splits and forms a blade to 30 cm (12 in) tall. The delicate, light green to medium green and transparent blade is due to a single layer of cells creating a blade only 30 μm thick. Cells are ~16 μm on a side. Habitat: This species occurs in the spring on protected and semi-protected coasts and can grow epiphytically on other seaweeds such as Fucus. Similar taxa: Kornmannia, Protomonostroma, Ulvaria.