We found it on the beach today.is it real?KZN south Africa

[MartinRSA]

Its 12mm - 13mm if you put a light behind it you can see layers inside.

 

[SteveM]

Certainly looks like a clam pearl, and assuming you're on the east (Indian Ocean) coast, as that is within Tridacna Sp. habitat. Hard to believe an ejected pearl would just wash up and retain its luster like that, couldn't have been there long. Whether a pearl or not would require a pearl lab or other qualified expert to determine whether those layers you see conform with symmetrical pearl growth.