[Solved] An operculum is a part of the sporophyte generation of a moss. Naked Eye: Relating to the ability to see or observe an object or event unaided by any optical instruments, such as telescopes or microscopes. Sandstone: A sedimentary rock consisting of sand-sized mineral particles or rock fragments compacted and cemented together. Natural Cements: Substances that occur in nature, which can act to bind materials together through a chemical or physical process. Clasts: Fragments of rocks or minerals that are embedded in a larger rock matrix, often found in sedimentary rocks.