If a new animal was discovered that spent half of its life underwater breathing films and half of its life on land breathing with lungs which group of animals would it fit into?

The newly discovered animal would fit into the group of amphibians. Amphibians are characterized by their dual life stages, typically spending part of their lives in water as larvae with gills and part on land as adults with lungs. This unique adaptation allows them to thrive in both aquatic and terrestrial environments. Examples of amphibians include frogs and salamanders, which exhibit similar life cycles.