11. Veiltails are available in many colors and may have either metallic or nacreous scales. 12. Conversely, the nacreous layer is derived from the main surface of the mantle. 13. Like noctilucent clouds, nacreous clouds are rare for our latitude here in South Florida. 14. The shell is more or less nacreous all over under a thin porcellanous upper layer. 15. In the living animal, the interior of the valves is nacreous and tinged pink. 16. But the beauty of pearls is literally a reflection of their surface and subsurface nacreous layers. 17. The mirror had now completely pearled, with nacreous yellows and purples rippling the silver-gray. 18. When the transition to nacre secretion occurs, the brown pebble becomes covered with a nacreous coating. 19. The nacreous layer of the aragonite fossil shells of some extinct ammonites forms an iridescent material called ammolite. 20. Those that show mother-of-pearl colors are given the name " nacreous ".
