pyrena

lang=en|thumb|Diagram of a typical drupe, in this case a peach, illustrating the layers of both the fruit and the seed; the pyrene is the hardened [[endocarp which encloses the seed]]

A pyrena () (: pyrenae) or pyrene, commonly called a pit or stone, is the fruitstone inside certain types of fruit, namely drupes or drupelets, and consists of a hardened shell-like layer surrounding one or more seeds (also called the "kernel"). It is produced by the hardening of the inner lining tissue of the fruit, called the endocarp. This hardened structure provides a protective physical barrier around the seed, shielding it from pathogens and herbivory.