How Much Seashells Did Sally Sell?

Terry Sullivan's 1908 tongue twister, "She sells seashells," according to P. J. McCartney in Henry de la Beche (1978), is based on Mary Anning's life as a English fossil collector, dealer, and palaeontologist
She sells seashells on the seashoreThe shells she sells are seashells, I'm sureSo if she sells seashells on the seashoreThen I'm sure she sells seashore shells.
There is no mention of how many shells "she" sells. If we wanted, we could make up a suitable line, such as:She sells seventy shells to see at the seashore;She sells her seventy seashore shells from the sea.