Two features of the gameplay are based on actual dolphin habits: one button causes Ecco to sing, allowing him to speak with other cetaceans and interact with certain objects. The same button is used for echolocation: holding it down causes the song to return, generating a map of the area. Several levels contain enormous crystals called "glyphs", which respond in different ways if Ecco touches or sings to them. Some block paths, and a "key-glyph" must be found in such cases to pass. Others give information, and a few in later levels replenish health/air and give Ecco temporary invulnerability.