@fishin,
I get the town's descriptive term. Kettle ponds are not (or are not necessarily) moving water - no spring in, no leakage out). Yet they somehow sustain water levels (rainfall only in some cases?) and their own ecology.
Anyway - all ponds on the Cape aren't kettles, I don't think. Though the ponds that aren't that I can think of, are man-made and usually involve us mucking around with the natural salt-water inlets.