Red starfish

This is the starfish everyone photographs in Malta, and for good reason: it is a uniform, saturated vermilion to orange-red that nothing else on the reef matches. Five slim, cylindrical, slightly tapering arms radiate from a small central disc, and the arms are gently rounded rather than flattened. Up close the skin looks granular and spiny, but run a finger near it and you will see it is coated in slippery mucus; it feels soft and soapy, not prickly. Arms commonly reach ten to fifteen centimetres, giving a span of twenty to thirty centimetres in a big one.

Look for it draped over the vertical face of a boulder, on the roof of a shallow overhang, or picking its way across the sand between Posidonia clumps. It is happy from a metre or two down to well beyond recreational depths, but around the Maltese islands most sightings are in the five to twenty-five metre band on mixed rock and sand: Xwejni, Ċirkewwa, Ġnejna and pretty much any rocky shore dive will produce one.

It moves at a pace you can watch if you stay still, sliding on hundreds of pale tube feet along a groove under each arm. It grazes on the thin film of sponge, bacteria and algae coating the rock rather than hunting prey, so it tends to sit for long periods on a single patch. In good light you can sometimes see clusters of soft, colourless finger-like gills pushed out through the skin between the spines.