Ashley's Stopper Knot is also known as the oysterman's stopper, is a knot developed by Clifford W. Ashley around 1910.
It makes a well-balanced trefoil-faced stopper at the end of the rope, giving greater resistance to pulling through an opening than other common stoppers.
Essentially, the knot is a common overhand noose, but with the end of the rope passing through the noose eye, which closes upon it.
It may be multiplied to form a larger knot with more than three bights appearing around the knot. It is the result of implementing a double wall knot in one strand.
Ashley developed this knot in trying to duplicate a knot he saw on a boat in a local oyster fishing fleet. When he had a chance to observe the knot up close at a later time he realized it was just a badly water-swollen figure eight stopper knot.