Common bossed bracelets / anklets banagiri muschawwaka. Matching pair. Bossed bracelets of one sort or another were worn throughout Oman.
Some believe that these were originally fertility anklets, with the bosses representing breasts. These anklets / bracelets were typically worn by married women or girls form the age of fourteen.
The slide-show contains an 1847 photo by Guillain (part of the collection of Musee du Quai Branly in Paris ) showing the niece of the governor of Zanzibar wearing a similar spiked bracelet on her left arm.