Years ago, when working as a conservation biologist in Ecuador, I came across large pale snails stuck fast to trees, aestivating (like hibernation, but caused by dry heat) in the sun-baked coastal dry forest. After sending empty shells to London's Natural History Museum, I received a note from its mollusc department identifying them as Porphyrobaphe iostoma, and asking if they could keep the shells since the species hadn't been seen for over 100 years. This is far from unusual. As Helen Scales shows in Spirals in Time, there are an awful lot of snails about which we know next to nothing. But then, there are some whose behaviour, biochemistry, genes and anatomical structure have been studied exhaustively.
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