At the base of the stalk is the holdfast , which cements the alga to the rock and prevents it from being washed away.
The rostellum ends in a holdfast by which the cell is fixed to the gut wall of its host.
Furthermore, the facts that crowns and holdfasts rarely occur attached but that each is preserved with attached incomplete columns, suggest that crowns were broken from their holdfasts prior to burial.
The algae were decapitated, clamped with vice grips at their holdfasts , and secured to the bottom of a unidirectional current tank with an ordinary house brick.
Lattice panels, wires, or rough surfaces give tendrils and holdfasts a place to latch onto.
Heavy grazing may damage and weaken the holdfasts which anchor the algae.
Crowns commonly have some length of column still attached, and holdfasts , less commonly recognized than crowns, also have some length of column attached.