Because they spoil at high temperatures, what were once assumed to be safe for eating only in the months with the letter 'r' in their English/French names?
Namagaki Oyster spat Oyster bed Kaki no dotenabe Smoked oyster Oysters Oyster
kaki no dotenabe namagaki oyster spat smoked oyster oyster oysters oyster bed
oysters
WikipediaEntity
Oysters