What Smokey said. I'd bet there are either BBQ grills in place at a beach picnic area - or charcoal or evidence of old charcoal briquettes in the sand where you find these melted AL nuggets.
Thanks for reply. The chemists say that hydrocloric acid will have a negative impact on aluminum (melt). This was cleaned aggressively with said acid.
I was more interested in what you thought about the detailed South American style face upper left with the apparent baby on stomach (middle/middle). Maybe it is harder to see then I thought. Thanks again.