The Family Spirulidae is a group of deep-sea squids that possess a spiral-shaped shell, or gladius, inside their body. They are also commonly referred to as "ram's horn squid" due to the shape of their shell. Other synonyms or related terms for Family Spirulidae include Spirula, Spirulina, or Janthina spirals. While they are not commonly known or studied, these fascinating creatures have unique adaptations, such as bioluminescence and the ability to control their buoyancy, that allow them to survive in their deep-sea environment. Studying the Spirulidae can provide insight into the evolution and adaptations of marine organisms.