I agree there are six "towers", but they clearly vary in thickness.
For the tower on the left, the narrow part is about 67% of the width of the globular section, while for the one on the right, the narrow section is only 25% of the width of the globe.
I didn't comment too much before since I didn't want to steer the vote, but I think we can also say that some of the objects are more tower-like while others are more vessel-like. The one on the right is the most like a vessel, with a foot for placing it on a table and a ringed stem for holding it in hand. But it also has some properties of a tower, most notably that there is no clear way of opening it and accessing the contents. The one on the left has the opposite problem: it stands broad and firm like a tower, but appears to have a lid so it could be opened like lidded chalice.
Mark brought up ciboria, which are excellent parallels. Look at this c. 1400 example and you will see what I mean:
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The lid checks out with the left tower but not with the right. The lower section checks out with the right tower but not with the left.
I voted 'both vessels and towers'