Ralfsia verrucosa forms roughly circular patches that grow outwards from the centre with the central parts sometimes becoming detached from the substrate.

[4] Ralfsia verrucosa is a cosmopolitan species and is found in temperate waters in northern and western Europe, Mediterranean Sea, Iceland, Greenland, Canada, New England, Argentina, round the coasts of Africa, India, Japan, Korea, China, Russia, Indonesia, Australia and New Zealand.

[3] Round the coasts of South Africa, Ralfsia verrucosa enjoys a mutual relationship with the limpet Scutellastra longicosta.

This limpet clears an area of rock by intensive grazing, and allows Ralfsia verrucosa to settle on it while excluding other species of algae.

The limpet then cultivates its "garden", grazing the algal turf to a moderate level and fertilising it with faeces and mucus.