Nudibranchs are shell-less sea slugs that usually bear their gills conspicuously on the back side of their bodies. In addition, they more often than not rely on chemical substances rather than on a shell for overall protection. The sea slug Polycera hummi Abbott, 1952 (photo) may reach about 20 mm (a little less than an inch) in size, and may be found from North Carolina through Florida and the Gulf. That colorful species was named in 1952 by Shell Museum's Founding Director Robert Tucker Abbott, and was first found on Sanibel in 2015 by Rebecca Mensch. The one in the photo was collected in February 2019 near the Sanibel Causeway, by Lorin Buckner. Read more about local mollusks and their shells in our Southwest Florida Shell Guide.