A seed is the reproductive unit of flowering plants, known as angiosperms. It contains an embryo, which can develop into a new plant, and is often encased in a protective outer covering. Seeds are formed from the fertilization of an ovule and can vary greatly in size, shape, and structure, depending on the species. The origin of seeds dates back to the evolution of plants over millions of years. The first seeds appeared around 360 million years ago, marking a significant advancement in plant reproduction. This development allowed plants to spread more effectively and adapt to various environments, contributing to the diversity of life on Earth.