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The animal on the cover of IPv6 Essentials, Second Edition, is a rigatella snail. The rigatella snail (Eobania vermiculata) is native to the Mediterranean region, especially to Turkey and Crete. The snail lives in gardens, hedges, and dunes, where it feeds on vegetation. The snail got its scientific name because the rings on its shell resemble vermicelli (a type of pasta). It is also sometimes called the "noodle snail."
Rigatella snails commonly have about five brown rings on their cream-colored shells. Their eyes sit on stalks, or tentacles, which protrude from their heads. The snails are 17 to 21 millimeters high and 20 to 25 millimeters wide. They move by rhythmically contracting their muscular base, or foot. As they move, the snails secrete a colorless discharge that creates a type of carpet, which protects them from the surfaces on which they travel. This discharge is so effective that a snail could crawl along the blade of a razor and not be cut.
Rigatella snails are edible. They are one of the most popular types of snail used to make the European delicacy, escargot.
The cover image is a 19th-century engraving from Cuvier's Animals. The cover font is Adobe ITC Garamond. The text font is Linotype Birka; the heading font is Adobe Myriad Condensed; and the code font is LucasFont's TheSans Mono Condensed.