Colonies are small bushes or tangles of thin branches up to about 25 cm across on fore-reef slopes. In sheltered, sedimented or lagoonal areas, however, colonies reach 1 m across. Branches are usually 1-4 mm thick and are sharply pointed and fragile. The linear alignment of calices is very noticeable, and calices are markedly oval in most cases. S. hystrix occurs over a wide range of depths, but is particularly abundant in shallow water in sheltered conditions. It is most abundant in back reef of lagoonal areas where colonies can cover up to 30% of the substrate (Sheppard, 1998). Branches are tapered to a point; they may be either widely spaced or compact. Colour: cream, blue or pink. Abundance: common in all shallow reefal environments (Veron, 1986). Easily recognisable. Fine branches (1.5-4.5 cm thick) with tapering tips; corallites (up to 1.5 mm across) in neat rows, slightly hooded. Forms compact shrub-like colonies. Colour: delicately coloured in cream, blue or pink. Habitat: shallow outer reef areas and sheltered inner algal and seagreas beds (Richmond, 1997); rocks (Kalk, 1959).