I love when I encounter atypical flora and fauna in fiction. Any details, large or small, to take me out of generic pine or deciduous forest and immerse me within in your world are welcome. And I love when the, shall we say, less noble creatures appear. Cats and deer are all well and good, and I intend to cover unique species of these subtypes. But there are just soooo many other things your characters could encounter.

Consider: You’re walking through a lightly forested area, walking slowly as you scrutinize your surroundings. A decaying log has fallen to nearly block your path, and you take note of an odd bump jutting from it. But wait. Is it… moving? Quickly you stride to the fallen timber and bend over for a closer examination. The bump has an odd spiraling conical shape to it, like a staircase following the outside of a tower, ending in a bit of a point. There’s something oozing from the base of the object adhering it to the rough bark, and as you watch it slowly flows over bumps and crevices and the shell is pulled along with its movement. You clamber over the log to get a look at the other side, and pull back in startlement when you realize it has two stalks emitting from the oozy base. And they seem to be following you.
Now, Giant African Land Snails have a size limit. Still startlingly huge, as they can easily weigh over a pound and become much larger than your hand. But that doesn’t mean they have to stay that small in your world. And think of the fun you could have! Snails emit mucus that they leave in their wake. This slime works both like a lubricant, allowing the gastropod to move, and also like a glue, allowing the gastropod to climb up and over various objects that stand in their way. Snail slime is currently one of the hot additions to facial masks and serums, possessing hyaluronic acid (which has a fair amount of evidence supporting its efficacy) and anti-oxidants (of more debatable benefit, but very in vogue in various forms).

Snail shells can be startlingly beautiful. Consider the possibilities of tinkering with what snails make their shells out of for your story. Mother-of-pearl is contained on the inner parts of gastropod and mollusc shells in the real world, and is utilized in many decorative fashions. Perhaps your snails could create other fine substances.
Also, snails are edible. (As someone lucky enough to be without texture issues in food, I find them to be a perfectly acceptable vehicle for moving cheese and garlic butter to my mouth.) Think about your reaction to having to hunt down, cook, and eat a Giant African Land Snail. How much would your character enjoy that experience, do you think? Would some of them take a perverse pleasure in it, and maybe some of them shudder and go on a food strike until they are so weak from starvation they have no choice?
I mean, it’s possible that I’m one of the few that think that would be a great deal of fun to put my characters through, and discover how each of them would react. But I doubt it.
