The bowls were broad and shallow, common in any household and used for cooking or perhaps for serving food. More significantly, they were also used in the tabernacle of the Old Testament (e.g., Exodus 25:29). Those used in the tabernacle were constructed of pure gold, as is fitting for the house of the Lord.
8 And when he had taken the scroll, the four living creatures and the twenty-four elders fell down before the Lamb, each holding a harp, and golden bowls full of incense, which are the prayers of the saints.