A mortar and pestle is a useful (and old-fashioned) way to grind up herbs, garlic, chilis or whatever ingredients you like - into a paste like consistency. It's also great for grinding spices. The mortar is the bowl, and the pestle the grinding tool that does all the actual work. For obvious reasons, mortars and pestles are generally made out of very durable materials, such as marble, stone or even cast iron. They need to be durable, because they really take a beating!
Here are a couple of examples of good, heavy-duty mortars and pestles: