periostracum /per-i-osˈtrə-kəm/

The horny outer layer of a mollusc's shell

• raree-show
• raree-shows
• rarefaction
• rarefactions
• rarefactive
• rarefiable
• rarefied
• rarefies
• rarefy
• rarefying
• rare gas
• rare groove
• rarely
• rareness
• rarenesses
• rarer
• rare-ripe
• rarest
• raring
• rarities
• rarity
• ras
• RAS
• rasae
• rascaille