What happens to your fingertips when you spend too much time in a bathtub?

When you spend too much time in a bathtub, your fingertips become wrinkled due to prolonged exposure to water. This happens because the outer layer of skin absorbs water and swells, causing the skin to pucker. This wrinkling is thought to be an evolutionary response that enhances grip on wet surfaces, although the exact mechanism behind it is still being studied. Once you leave the water, your fingertips gradually return to their normal appearance as the skin dries out.