The avagraha sign in the Bengalialphabet. It represents the same sound as the Devanagari sign ऽ, that marked extended length in Sanskrit, and still used sometimes for regularizing the scansion in poetry or songs, or as a common abbreviation for a long sound, where it elides a following leading vowel 'a' within words or at start of the next word, with the preceding vowel (a common kind of prodelision in Indic languages).
