21. The inner edge of the outer lip is golden-brown and white, interior shining and nacreous . 22. It is a naturally occurring, non-nacreous , calcareous concretion ( pearl ) from a giant clam. 23. Sometimes, the aragonite forms an inner, nacreous layer, as is the case in the order Pterioida. 24. It may take several months for the nacreous coloration to develop on a young fry ( baby fish ). 25. Three years later, Henrik Mohn revealed a similar discovery of nacreous clouds in what is now considered the stratosphere. 26. Although non-nacreous , the surface of fine conch pearls has a unique and attractive appearance of its own. 27. Both these and non-nacreous types are classified alpha-numerically according to their physical state and chemical makeup. 28. An ancient-looking stone grotto is illuminated with the nacreous glow of hundreds of abalone shells affixed to the walls. 29. "' Pearl Maxima "'is one of the largest true pearls or nacreous pearls in the world. 30. The base is the same color as the body, and the interior of the aperture is nacreous ( pearly ).
