This is quite interesting.
First of all, Anne, I take your point exactly that it is like the Melon Rib pieces we were discussing. The Carnival vases (mainly found in Australia) that bear the name Melon Rib (given by collectors) have horizontal ribs/panels. But these vertical ribs are what glass collectors more often refer to as Melon Ribs.
But, we all know how contrary Carnival collectors can be :lol: and I think this item that you've found, Christine, is actually Imperial Glass' Pillar Flute pattern (Imperial's #682).
It gets interesting though, as it is not the shape usually known as the sugar bowl. There is a 2 handled sugar that matches a little creamer. These two items have stubby squared off feet. Then there are bowls - mostly on a collar base. But your piece has a distinctive plinth type of foot. Most items in the range do not have that foot - except for two pieces I can see that have the exact same one that yours has. One is a 7" flared (very low and wide) comport - the other is more like yours, but with a slight outward flare at the top - and the shape is descibed as a mayonnaise (there was also a small ladle).
So I think that's what you have - a cupped in mayonnaise dish. Bring on the Hellmann's!