I’m thinking these firm, brown 4 inch-wide items from a Sarasota neighborhood are NOT actually nuts. Maybe not even fruits.
It looks to me like there are root and shoot buds showing on the surface, and maybe this tropical tree presumed vegetative growth would float, find its way to land elsewhere, sprout roots and shoots, and thus become established in new territory.
That story could be all wrong.
Surely somebody will recognize these lumpy unknowns. Anyone?