The type Spurilla neapolitana is found in the eastern Atlantic Ocean, from Cape Verde and the Azores to Portugal, and in the Mediterranean Sea.

These tips are known as cnidosacs and are defensive structures armed with cnidocytes (stinging cells) garnered from sea anemones that the nudibranch has eaten.

[3] The general colour of this species is orange or pinkish, perhaps depending on what it has been eating, often with dark streaking where the tortuous digestive gland is visible through the translucent skin and the walls of the cerata.

The cnidocytes pass unharmed through the gut of the nudibranch to the tip of the cerata where they are stored, to be used in the animal's defence.

[6] The nudibranch's tissues harbour live intracellular zooxanthellae (photosynthetic single celled organisms), also derived from the sea anemone.