Are they snails? They are in mulch of my mulberry tree. I read they are dangerous to plants. What should I do?
Snails eat anything, including each other, so they like fresh green and growing leaves (usually young leaves) and decaying matter such as dead leaves and other materials that may be present in mulch. They usually appear after dark, and they love wet/damp places and weather. They are not dangerous nor particularly harmful, but if, say, you were growing lots of lettuce or other leafy crop, they'd probably eat quite a lot before you do. They are a particular risk in spring, when they will eat emerging growth of some plants such as Delphinium. I don't think your mulberry tree leaves are particularly at risk, but if you want to limit your snail and slug population, there are many products available, from organic solutions to nematodes and pesticides. Google 'slug and snail control' and that should reveal many products.