This includes snails, slugs, clams! Not to mention octopus and 'sotong'.In Science-speak, these included: one polyplacophora species, 97 bivalvia species (30 families), 155 gastropoda (48 families), and five cephalopoda (five families).
A cuttlebone and an empty Nautilus pompilius shell also offer intriguing possibilities.
There's also a great GIS map of Pulau Semakau in the article.
Download and read the article from Nature in Singapore: Tan, S. K. & R. K. H. Yeo, 2010. The intertidal molluscs of Pulau Semakau: preliminary results of “Project Semakau”. Nature in Singapore, 3: 287–296. [PDF, 200 KB]
Although there are no photos in the Nature in Singapore article, you can have a look at some photos on the Project Semakau site.
More about Pulau Semakau and about Singapore's molluscs on wildsingapore.
