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Soft rock, such as chalk, in the sublittoral fringe characterised by Laminaria digitata and rock-boring animals such as piddocks Barnea candida and Pholas dactylus, the bivalve Hiatella arctica and worms Polydora spp. Beneath the kelp forest, a wide variety of foliose red seaweeds occur such as Palmaria palmata, Chondrus crispus, Membranoptera alata and Halurus flosculosus. Filamentous red seaweeds often present are Vertebrata fucoides and Ceramium nodulosum, while coralline crusts cover available rock surface. The bryozoan Membranipora membranacea and the hydroid Dynanema pumila can form colonies on the kelp fronds, while the bryozoan Electra pilosa more often occur on the foliose red seaweeds. Empty piddock burrows are often colonised by the polychaete Sabellaria spinulosa or in more shaded areas the sponges Halichondria panicea and Hymeniacidon perlevis. The undersides of small chalk boulders are colonised by encrusting bryozoans, colonial ascidians and the tube-building polychaete Spirobranchus lamarcki. The boulders and any crevices within the chalk provide a refuge for small crustaceans such as Carcinus maenas, the mussel Mytilus edulis or the barnacle Semibalanus balanoides. The echinoderm Asterias rubens is present as well.