An unusual form of gypsum is reported from Deer Cave, Gunung Mulu National Park, Sarawak, Malaysia. The gypsum is originally derived from decomposing bat guano, is air-dispersed, dissolved in condensation water entrained in spiders' webs, and then recrystallized on the spider silk matrix.

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Journal Cave and Karst Science
Lundberg, J, & McFarlane, D.A. (Donald A.). (2017). Speleothems and spiders: Morphology and origin of gypsum nucleated on spider webs, Deer Cave, Sarawak, borneo. Cave and Karst Science, 44(3), 127–131.