Semantron

A Russian monk playing a semantron

The semantron (Greek: σήμαντρον) is a percussion instrument used in Eastern, Oriental Orthodox and Eastern Catholic monasteries to summon the monastics to prayer or at the start of a procession.

It is also known as a semandron, semanteriom (σημαντήριον), simantra (σήμαντρα), xylon (ξύλον) and talanto (ταλαντο). In other languages, it is called as follows: Romanian: toacă; Russian: било, bilo; Bulgarian, Macedonian, Serbian: клепало, klepalo; Arabic: ناقوس, nāqūs; Armenian: կոչնակ, kochnak or gochnag.