The most important thing to learn about the OSI model is what it really represents. Pretend you're an operating system on a network. Your network card, operating at layers 1 and 2, will notify you when there's data available. The driver handles the shedding of the layer 2 frame, which reveals a bright, shiny layer 3 packet inside (hopefully).
Used with permission. Agate is a variety of chalcedony, a cryptocrystalline form of quartz. Translucency, patterns of color, or moss-like inclusions may distinguish this stone from other forms of chalcedony. Agates can show a wide variety of vivid, multiple colors.
Agate is a translucent variety of microcrystalline quartz. It is used as a semiprecious stone when it is of desirable quality and color. Agate generally forms by the deposition of silica from groundwater in the cavities of igneous rocks. The agate deposits in concentric layers around the walls of the cavity, or in horizontal layers building up from the bottom of the cavity.