Molluscs

https://www.nature.com/articles/ngeo1635: Extensive dissolution of live pteropods in the Southern Ocean | Nature Geoscience
https://news.nationalgeographic.com/news/2011/04/110414-eyes-rock-crystal-mineral-chiton-mollusk-vision-animals-science/: Eyes Made of Rock Really Can See, Study Says
https://www.nationalgeographic.com/animals/invertebrates/g/giant-squid/: Giant Squid | National Geographic
https://en.wikipedia.org/wiki/Glaucus_atlanticus: Glaucus atlanticus - Wikipedia
https://en.wikipedia.org/wiki/Janthina_janthina: Janthina janthina - Wikipedia, the free encyclopedia
http://www.scientificamerican.com/podcast/episode/octopus-skin-senses-light-no-eyes-or-brain-needed/: Octopus Skin Senses Light, No Eyes or Brain Needed - Scientific American