Insular S
Insular form of the letter S (Ꞅ)
From Wikipedia, the free encyclopedia
The letter Ꞅ (minuscule: ꞅ) is an Insular script form of the letter S. The uppercase is encoded in Unicode at U+A784,[1] and the lowercase is encoded at U+A785 [2]

It should not be confused with the long-legged r, U+027C ɼ LATIN SMALL LETTER R WITH LONG LEG, which is an obsolete IPA symbol.