The outer surface encloses the ergosphere and has a shape similar to a flattened sphere. It encloses the pericardial cavity which contains pericardial fluid. The gas centrifuge is designed with a casing that completely encloses the centrifuge. It encloses the thoracic cavity, which contains the lungs. A boundary wall encloses the two temples. The diencephalon encloses a cavity called the third ventricle. Consequently, the snowflake encloses a finite area, but has an infinite perimeter. The monument's boundary encloses an area of . The lower part of each leaf encloses the stem, forming a leaf-sheath. Microvilli are covered in plasma membrane, which encloses cytoplasm and microfilaments. As the seed matures, a fleshy aril partly encloses it. The area is protected by a fence that completely encloses it. It encloses Frederiksberg Municipality and stretches east to the waterfront. Lastly, the epithelium or tunica propria encloses the gland. The computer case encloses and holds most of the components of the system.