An interesting theory, one that I have not heard of. However I wonder if the
species is G. cosmoi, which Powell considered a subspecies of congener but is
now generally regarded as a valid species. In this there is characteristically
a "frilly" lip edge from the 3 primary subperipheral spirals enlarging once
the shell gets big enough. This can look odd, deformed even. The same thing
happens on a couple other of the gemmate turrids but not as regularly. This
architecture is to be distinguished from what has been called an "accesory
sinus." This is a sinus-like, nearly tubular protrusion from the lip edge
below the level of the 3 primary spirals. It occurs in Ptychosyrinx spp., such
as bisinuata Martens, 1901. This has been regarded as an aging feature, but it
occurs almost uniformly once the shell is beyond juvenile age and size, so I
suspect an inherited cause. At least a tendency to it. The same thing is seen
in other Gemmulas--Pinguigemmula thielei and others of this, now, subgenus,
plus, yes, G. congener. Interesting feature.
 
Donn