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Sabella spallanzanii is a species of marine polychaete worms in the family Sabellidae. It is native to the northeastern Atlantic Ocean, Mediterranean Sea and North Sea, but has spread to various other parts of the world and is included on the Global Invasive Species Database. The species grows to a total length of 9 to 40 centimetres (4 to 16 inches) and is usually larger in deep water. It features stiff, sandy tubes formed from hardened mucus secreted by the worm that protrude from the sand, and a two-layered crown of feeding tentacles that can be retracted into the tube. This S. spallanzanii worm was photographed in Arrábida Natural Park, Portugal.Photograph credit: Diego Delso