Here are a few different types of old artillery rounds that I found recently from times long ago...cannon balls from the 1800s and more modern brass encased rounds probably from the early 1900s, all were laying  on top of the sand and easily visible. A short boat ride away I found a bunch of beautiful old military buttons in brass, copper and pewter buried a few inches below the sand...all are embossed with different markings and were found only about 15' from the shoreline.