"Pyropia" species are red algae with a discoid holdfast and short stipe. The base has a short stipe arising from a rhizoidal holdfast. The organism had a holdfast, stalk and frond. It is also called the basal holdfast, which attaches the filament to the substratum. The thallus is perennial with an irregular or disc-shaped holdfast or with haptera. "Ulva lactuca" is a thin flat green algae growing from a discoid holdfast. It is composed of a thallus and a holdfast. The holdfast, a root-like structure, anchors the kelp to the substrate of the ocean. It grows from a discoid holdfast up to long. The macroscopic sporophyte has many specialized blades growing near the holdfast. "Polyides rotunda" is similar but can be distinguished by having a discoid holdfast. It is attached by a basal disc-shaped holdfast. A "holdfast" is a rootlike structure present at the base of the alga. The earliest genera had a short holdfast and irregularly structured plates. Seacliff is a suburb of Adelaide in the City of Holdfast Bay.