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Rhizoids are simple, hair-like projections that grow out of the epidermal cells of bryophytes.Rhizoids perform the function of roots, essentially anchoring the plants into the surface.Rhizoids of the bryophytes are unicellular or multicellular.

Fimbriae are long filamentous polymeric protein structures located at the surface of bacterial cells. They enable the bacteria to bind to specific receptor structures and thereby to colonise specific surfaces.

Holdfast plays the role to anchor the alga so that it stays in place on the substrate where it grows, this further helps to prevent the algae from being carried away. Hence the primary role of holdfast is to anchor the algae to the substrate.