"The Vayssiereidae is a remarkable family of microscopic nudibranchs that have no gills. Instead of taking place via gills, gaseous exchange occurs directly through the skin. Members of this family fed on very small polychaetes with spirally coiled shells of the family Serpulidae, subfamily Spirorbinae. Vayssiereids use the radula to drill through the calcareous shell of the tubeworm to reach the worm’s soft body inside."