The Valknut symbol in a form topologically equivalent to a closed three-link-chain.  See also Image:Valknut-Symbol-borromean.svg and Image:Valknut-Symbol-triquetra.svg .

Note that this form of the Valknut probably did not occur in medieval times (as versions of the Valknut equivalent to the Trefoil knot and the Borromean Rings linked above did).
This  vector image was created with a text editor.
Design and PostScript code by AnonMoos, first SVG conversion made by User:Erin Silversmith