ꙮ aka Мультиокулярная О is a variation of the Cyrillic letter О, made out of ten ocular Os. This symbol was used in some manuscripts, written in Old Church Slavonic, in the phrase ‘серафимимн҆огоꙮ҆читїи҆’ (‘many-eyed seraphim’).
This symbol exists in Unicode since v5.1, but until v15 it contained seven ocular Os instead of ten due to the low quality of a scan.