And just to add ... the "very coggy" canes as in the eBay weight are typical of 20th century Murano work, as are the colours used.
And yes, the unusual cane shapes that are sometimes seen in weights are very often simply distortions of round canes. If a real triangular (etc.) cane was used, there would very likely be several known examples that had a precise shape rather than variations. As seen in the eBay example, the inner row canes show as round, tear-drop, diamond and triangular, but they are all the same round cane as can be seen by looking closely at their lower sections - it's the tops that are distorted most of all.