In addition to fresh water shells, land snails also frequently have the colors and pattern in the periostracum, but not all of them, and sometimes this can be difficult to determine by looking at the shell. Some land snails have a fairly thick periostracum which obscures any pattern or color of the shell itself. Such shells are usually bleached to remove the periostracum, and generally such shells, once bleached, do have some color. Other land shells have a thin, translucent periostracum, which allows the shell colors and patterns to show through. Many collectors like to remove this kind of periostracum, since it may give a yellowish cast to the shell, and mute the colors. However, this is where collectors may run into trouble. In some land snails, all the color and pattern are in the periostracum, rather than the shell. Others have colors and markings in both shell and periostracum, and the appearance of a fresh specimen is actually an overlay of the periostracal pattern over the shell pattern. Bleaching shells of this kind can provide some interesting (or disastrous, depending on your point of view) results. The beautiful, large, green-banded Helicostyla portei, if exposed to bleach, will come out as white as a snowball. It's color and pattern are entirely in the periostracum. Incidostoma confusum, a large operculate land snail from South America, appears bicolored in natural condition, the upper half of the shell light brown, the lower half dark brown. After bleaching, it is pure white, except for a pink apex. In some Chrysalis species the spiral, or transverse markings are on the shell, but the axial markings are a periostracal overlay. Bleach it and you have spiral pattern only. Helicostyla grandis in life appears light greenish brown with multiple bands and irregular splotches of dark chocolate brown. After bleaching, it is uniformly dark brown, fading to white toward the apex. The light brown color seen in life is periostracum, and the dark bands and "markings" are actually uncolored, transparent areas of periostracum, where the underlying dark shell color shows through. Placostylus hargravesi, a beautiful, elongate, olive-colored shell with intricate darker markings also bleaches pure white - except for the interior columellar area, where the periostracum was overglazed by the snail! Helicostyla pan is another interesting one, a very attractive shell, both before and after bleaching. Before bleaching it has multiple spiral bands ranging from deep chocolate brown through lighter brown, tan, and white. After bleaching, the banding is gone. The lower half of the body whorl is deep chocolate brown, which extends up along the suture line. The upper half of the body whorl is tan, fading to white near the brown suture. The shell also has a nice gloss, another feature which is hidden by the periostracum. So, while many land shells can be bleached safely, if you aren't sure, try your least desirable specimen first, and avoid unhappy surprises.