The Ulva Clathrata could be cylindrical or compressed with narrow branchlets as much. It has less than 30 cm long. It has too repeatedly branched in all directions, (40cm long). It is light green in colour. This alga is composed of highly branched, hair-like, hollow filaments which connect at a small holdfast. However, in nature, many plants become intertwined and not easily distinguished, forming instead a dense mat, almost resembling a lawn or a bed of moss. This species can be distinguished from other filamentous species by microscope - more than one cell layer make up the thallus, which has a hollow medulla.

This species forms tufts, bright green, composed of branched axes, which can reach several centimeters long (20-30 cm). The main axis and branches are covered with conical branchlets very characteristic.