It doesn't rain very often here, but when it does, an incredible number of mollusks are suddenly evident. There are several sorts of slugs and land snails. Most of the snails aren't very large, but I've found shells of some that are almost an inch in diameter. The snails come in different shapes including almost round shells to stream-lined pointy shells. The shells are all very fragile, thin-walled and brittle.
During dry weather, the snails attach to a surface and "glue" themselves to it with mucus, which hardens and keeps the snail from losing its body moisture. I have sometimes found them right in the hot sun and I wonder how they keep from being cooked.
After a good rain, the snails come out to feed and crawl all over the place, including in the trees. They travel, like slugs do, on a carpet of slime they produce, which later dries and leaves a glistening trail. Even though snails are fun to watch, they do quite a bit of damage to small seedlings as they eat all sorts of vegetation. However, considering our inhospitable conditions, they are not a problem most of the time. During especially long hot dry periods, many snails die and there are a lot of areas where the soil is littered with bleached white shells, reminiscent of a beach.
Snails feed by sweeping back and forth over the surface, using their rasping tongue to scrape off the outer layer of plants or algae on hard surfaces. The final photo here is of a snail's feeding marks on the bark of a tree.