Neutral Yer

Neutral Yer (Majuscule: Ꙏ, Minuscule: ꙏ) is used in transcribing documents when it is hard to tell the difference between a Ь and a Ъ. It was common in Late Medieval Russian archival materials and scripts.

Cyrillic letter Neutral Yer
The Cyrillic script
Slavic letters
А Б В Г Ґ Д Ђ Ѓ Е Ѐ Ё Є Ж З З́ Ѕ И Ѝ Й І Ї Ј К Л Љ М Н Њ О Ō П Р С С́ Т Ћ Ќ У Ӯ Ў Ф Х Ц Ч Џ Ш Щ Ъ Ы Ь Э Ю Я
Non-Slavic letters
А́ А̀ Ӑ А̄ А̊ А̃ Ӓ Ӓ̄ Ӕ Ә Ә́ Ә̃ Ӛ В̌ Ғ Г̧ Г̑ Г̄ Г̣ Г̌ Ҕ Ӻ Ғ̌ Ӷ Ԁ Ԃ Ꚃ Ꚁ Ꚉ Д̆ Д̣ Ԫ Ԭ Д̆ Ӗ Е̄ Е̃ Ё̄ Є̈ Ӂ Җ Ꚅ Ӝ Ԅ Ҙ Ӟ З̌ З̱ З̣ Ԑ Ԑ̈ Ӡ Ԇ Ӣ И̃ Ҋ Ӥ И́ Қ Ӄ Ҡ Ҟ Ҝ Ԟ К̣ Ԛ Ӆ Ԯ Ԓ Ԡ Ԉ Ԕ Ӎ Ӊ Ң Ԩ Ӈ Ҥ Ԣ Ԋ О́ О̀ О̆ О̂ О̃ Ӧ Ӧ̄ Ө Ө̄ Ө́ Ө̆ Ӫ Ҩ Ԥ Ҧ Р̌ Ҏ Ԗ Ҫ С̣ С̱ Ԍ Т̌ Т̣ Ꚑ Ҭ Ꚋ Ꚍ Ԏ У̃ Ӱ Ӱ́ Ӳ Ү Ү́ Ұ Х̣ Х̱ Х̮ Х̑ Ҳ Ӽ Ӿ Һ Һ̈ Ԧ Ꚕ Ҵ Ꚏ Ҷ Ӵ Ӌ Ҹ Ꚓ Ꚗ Ꚇ Ҽ Ҿ Ы̆ Ы̄ Ӹ Ҍ Э̆ Э̄ Э̇ Ӭ Ӭ́ Ӭ̄ Ю̆ Ю̈ Ю̈́ Ю̄ Я̆ Я̄ Я̈ Ԙ Ԝ Ӏ
Archaic letters
Ꙁ Ꙃ Ꙅ Ꙇ Ꙉ Ҁ Ѻ ОУ Ꙋ Ѡ Ѽ Ꙍ Ѿ Ꙏ Ѣ Ꙑ Ꙓ Ꙕ Ꙗ Ѥ Ѧ Ꙙ Ѫ Ꙛ Ѩ Ꙝ Ѭ Ѯ Ѱ Ѳ Ѵ Ѷ Ꙟ Ꙡ Ꙣ Ꙥ Ꙧ Ꙩ Ꙫ Ꙭ ꙮ Ꚙ Ꚛ
List of Cyrillic letters Cyrillic digraphs

The appearance looks like a Yer with a hook on the top.