Stones fastened in bows

1. Mosiah 28: 13
     13 And now he translated them by the means of those two stones which were fastened into the two rims of a bow.
2. JS-H 1: 35
     35 Also, that there were two stones in silver bows—and these stones, fastened to a breastplate, constituted what is called the Urim and Thummim—deposited with the plates; and the possession and use of these stones were what constituted “seers” in ancient or former times; and that God had prepared them for the purpose of translating the book.