A very old form is the "rose" or "rosette"; in this the extreme upper centre, called the "crown," or "star," is usually composed of six triangles, the Apexes of which are elevated and joined together, forming one point in the centre.
"The Chemistry, Properties and Tests of Precious Stones"
John Mastin
From their bases descend a further series of triangles, the bases and Apexes of which are formed by the bases and lower angles of the upper series.
"The Chemistry, Properties and Tests of Precious Stones"
John Mastin
The four piers of the crossing, though slender and graceful, carry full, logical complements of shafts for the support of the various vaulting ribs, intersecting at their Apexes.
"Cathedrals of Spain"
John A. (John Allyne) Gade