s A Field Guide to the British Seaweeds - NMBAQC

Calcareous encrusters
Calcareous encrusters incorporate a number of
Species from various genera including
Lithophyllum, Lithothamnion, Phymatolithon, and
Mesophyllum. They are very distinct forming a hard
coating over rock surfaces and occasionally on the
fronds of other algae such as Titanoderma which is
often found on Polyides. They grow in a variety of
colours ranging from light to dark pink, deep red
and purple and may also be slightly speckled with
the edges often bleaching. Not to be confused with
the basal portion of Corallina sp. They are found
throughout the littoral and sublittoral appearing in a
variety of forms including a smooth shiny surface,
lumpy, knobbly crusts, with smooth edges or highly
convoluted ridges. Very common.