epiphragm

noun
  1. A membranous or calcareous plate secreted by certain mollusks (especially land snails) to seal the opening of their shell during hibernation or dormancy.
  2. Usage: biology; zoology
  3. A similar sealing structure produced by some other organisms, such as certain amphibians or insects, to protect against desiccation.
  4. Usage: biology; specialized

Examples