A channel of deep blue green water separates the fringing reef flat of Semakau from Terumbu Raya, a plateau of rubble that rises from the sea during rare spring tides. The patch reef's sandy bottom and coral rock is hidden from view by a brown skirt of blooming sargassum. But with the aid of a non-problematic boat, friendly furniture and a stubborn refusal to acknowledge the possibility of falling off an aquatic cliff, it was possible to land with just the loss of a sound sense of mind. For the plectrum-shaped reef threatens to trap its uninvited guests in a bog of tidal pools which harbour creatures that seem a world away from the landward shore beyond the water. Polyps of hellfire, tiny shrimps with crusty shells and anglers on frog legs lurk amidst the pale weed and swirling minefield of invisible tentacles. Less concerned with camouflage, however, was a large nudibranch that my duck disturbed while it was minding its own business and busily draping a thin stream of vermilion over a low outcrop. The slug's size and tuberculate mantle caused my duck to mistake it for another robust species, but wiser hunters pointed to its probable true identity as a beast of foul repute. Variously dismissed as a clump, a brain, a liver, a foetid thing and a cutaneous rash, the unfortunate mollusc ended up with a shithole of a name bestowed by a taxonomist who might have been suffering severe gastro-intestinal irritability. It certainly explains my duck's unwhole fascination with an animal that probably reminded him of moments of glorious release that go plop!