Lunate mim?

[Dana]

Это про эстрангело или то, что ему предшествовало:

In some older manuscripts and inscriptions it is possible for any letter to join to the left, and older Aramaic letter forms (especially of Ḥeth and the lunate Mem) are found.

Шо за зверь такой?

[Python]

Все нагугливаемые упоминания о lunate mem ссылаются на копии одной и той же статьи википедии...

[Nārada]

Здесь имеется в виду округлая форма буквы мим:

In handwritten Greek during the Hellenistic period (4th and 3rd centuries BC), the epigraphic form of Σ was simplified into a C-like shape. It is also found on coins from the fourth century BC onwards.This became the universal standard form of Sigma during late antiquity and the Middle Ages. It is today known as lunate sigma (upper case Ϲ, lower case ϲ), because of its crescent-like shape.

(wiki/en) Sigma#Lunate_sigma