Like an abandoned cat, a silly old dog, or an old clown forgotten by his circus - I couldn't resist. In fact this is a tiny silver coin, dating from the early eleventh century and issued in what's now Pakistan. A breakaway kingdom of the Abbasids: the Habbarid dynasty of Sind, about whom not much is known. Amir Ahmad. 8 mm, 0.5 gr.
That's a nice little coin! Good to know that I'm not the only one who finds Habbarid coinage interesting. I've got an AE fals by Ahmad, the same ruler who issued your damma, and two little dammas of other Habbarid rulers: Habbarids of Sind, under Ali, AR damma, c. late 9th–10th c. AD. Obv: “b’allah yathiqu ali wa bihi yantasir.” Rev: “lillah muhammad rasul allah ali." 11mm, 0.52g. Album 1496. Habbarids of Sind, under Ahmad, AE fals, ca. 950–1000 AD. Obv: flower with four petals in double square. Rev: regents title and name in three lines, in central line "...mad" (part of name "Ahmad." 12mm, 1.05g. Apparently yet uncatalogued but some examples on zeno.ru. Ex Sikka Numismatics. Habbarids of Sind, under Abd Allah II, AR damma, c. early 11th c. AD. Obv: “la Ilaha Illa allah wahdahu la sharika lahu.” Rev: “muhammad rasul allah al-amir abd allah." 9.5mm, 0.62g. Album A1502.
Okay, it's yours. I hope you wait a long long time before you have to use it though. God willing and the creek don't rise! Good luck...