Terrestrial Snail Species - Danum Valley, Malaysia
Large terrestrial snails were commonly seen at night in the Malaysian rainforest. I am unsure of the species, keying out the particular ID for gastropods can be very difficult as there is a tremendous diversity of gastropods and I'm very far from an expert. I do suspect that this species falls into the superfamily Helicoidea, which contains 19 more families that I don't know enough about to narrow this specimen into one of those. Either way this large and impressive land snail seemed to double back onto itself and was doing something with its shell. Perhaps using its radula, a toothed chitonous ribbon used for scraping food into the esophagus, to scrape off some sort of growth on the surface of its shell?
EDIT: Thanks to ID help from Bernard Dupont, I think this is likely Hemiplecta humphreysiana, a large terrestrial snail found in Malaysia, Borneo and Sumatra.