Simplify the following text for a Grade 7 native English-speaking person.
Original: The fruit of these plants are known as stone fruit ( botanically , a drupe ) , as each fruit contains a hard shell ( botanically , the endocarp ) called a stone or pit , which contains the single seed .
Simplified: The fruit of these plants are known as stone fruit ( botanically , a drupe ) , as each fruit contains a single , hard-shelled seed called a stone or pit .