A cross composed of four interlaced triquetras, for a total of 20 crossings.  A slightly-differently proportioned version of this appears in the Sacramentarium of Rheims (e.g. http://www.esomogyi.com/rheims.html ).  For an alternative version (called a "Carolingian Cross" by Rudolf Koch), see Image:Triquetra-Cross.svg .

Since the Triquetra is a Trinitarian symbol, this cross could be considered to be an emblem of the Christian Trinity.  For other Trinity crosses, see Image:Cross-Bottony-Heraldry.svg , Image:Borromean-cross.png / Image:Borromean-cross.svg , and perhaps Image:Cross-Flory-Heraldry.svg .
vector PostScript source code given below; vector conversion of Triquetra-Cross-alternate.png
first conversion Snubcube, second conversion AnonMoos