The term 'SEED SHELLS' can be broken down into two words: 'HULLS' (5 letters) and 'SEEDS'. Hulls are the outer covering of a seed, which protects the seed from damage and helps it to germinate. Seeds are the reproductive units of plants, containing the genetic material necessary for the growth of a new plant. The combination of these two words, 'SEED SHELLS', refers to the protective outer covering of a seed, which is essential for its successful germination.