periostracum /per-i-osˈtrə-kəm/

The horny outer layer of a mollusc's shell

• aerospaces
• aerospike
• aerospike nozzle
• aerostat
• aerostatic
• aerostatical
• aerostatics
• aerostation
• aerostations
• aerostats
• aerotactic
• aerotaxes
• aerotaxis
• aerotone
• aerotones
• aerotrain
• aerotrains
• aerotropic
• aerotropism
• aerotropisms
• aeruginous
• aery
• aes alienum
• aesces
• Aeschna