In some of these islands pearl oysters are found, especially in the Calamianes, where some have been obtained that are large and exceedingly clear and lustrous. [114] Neither is this means of profit utilized. In all parts, seed pearls are found in the ordinary oysters, and there are oysters as large as a buckler. From the [shells of the] latter the natives manufacture beautiful articles. There are also very large sea turtles in all the islands. Their shells are utilized by the natives, and sold as an article of commerce to the Chinese and Portuguese, and other nations who go after them and esteem them highly, because of the beautiful things made from them. On the coasts of any of these islands are found many small white snail shells, called _siguei_. The natives gather them and sell them by measure to the Siamese, Cambodians, Pantanes, and other peoples of the mainland. It serves there as money, and those nations trade with it, as they do with cacao-beans in Nueva Espana. [115] Carabao horns are used as merchandise in trading with China; and deerskins and dye-wood with Japon. The natives make use of everything in trading with those nations and derive much profit therefrom. In this island of Luzon, especially in the provinces of Manila, Panpanga, Pangasinan, and Ylocos, certain earthenware jars [_tibores_] are found among the natives. They are very old, of a brownish color, and not handsome. Some are of medium size, and others are smaller, and they have certain marks and stamps. The natives are unable to give any explanation of where or when they got them, for now they are not brought to the islands or made there. The Japanese seek them and esteem them, for they have found that the root of a plant called _cha_ [tea]--which is drunk hot, as a great refreshment and medicine, among the kings and lords of Japon--is preserved and keeps only in these tibors. These are so highly valued throughout Japon, that they are regarded as the most precious jewels of their closets and household furniture. A tibor is worth a great sum, and the Japanese adorn them outside with fine gold beautifully chased, and keep them in brocade cases. Some tibors are valued and sold for two thousand taes of eleven reals to the tae, or for less, according to the quality of the tibor. It makes no difference if they are cracked or chipped, for that does not hinder them from holding the tea. The natives of these islands sell them to the Japanese for the best price possible, and seek them carefully for this profit. However, few are found now, because of the assiduity with which the natives have applied themselves to that search. [116]