yá
tooth
Depicts top and bottom teeth touching each other.
Evolution

Bronze script
Mid Western Zhou (~900 BC)
Seal script
Shuowen (~100 AD)
Clerical script
Cao Wei (Three Kingdoms: 222-280 AD)Regular script
ModernComponent uses
Unknown component in 1 character (0 verified)
Sources
季旭昇《說文新證》p.139-140