Mantle — Earth layer, ceremonial cloak, and mollusc organ

Geological mantle

In Earth science the mantle is the thick rocky shell lying between the planet's crust and its metallic core. It makes up most of Earth's volume and behaves as a solid on short timescales but slowly flows over geological time. Mantle convection — slow motion driven by heat from the interior — is a fundamental engine of plate tectonics and volcanic activity.

• Layers: commonly divided into upper mantle, transition zone, and lower mantle.
• Composition: dominated by silicate minerals richer in magnesium and iron than the crust.
• Processes: convection, partial melting, and mantle plumes influence surface geology.

Mantle as vesture

As clothing, a mantle is a loose, sleeveless outer garment or cloak historically worn for warmth or status. In many religious traditions an ecclesiastical mantle remains a ceremonial vestment for bishops and monastics, symbolizing authority or spiritual responsibility. The garment's form and ornamentation vary by culture and period.

Mollusc mantle

The mollusc mantle is a significant layer of tissue that envelops the visceral mass of molluscs and plays multiple roles. It secretes the shell in shelled species, forms the mantle cavity that houses gills or lungs, and participates in respiration, excretion and sensory functions. For more on body plans see molluscan anatomy.

• Shell formation: calcium carbonate deposited by mantle cells builds external shells in many gastropods and bivalves.
• Respiration and feeding: the mantle cavity accommodates gills, siphons, or other structures.

Despite shared imagery of a covering, these mantles function at very different scales and in different systems: planetary dynamics, human culture, and animal anatomy. Each meaning is important within its field and the word's versatility makes it a useful metaphor for layers that protect, conceal, or drive underlying processes.