I had not seen this before. We removed this old mid 90's Kohler Wellworth with plastic tubing for the siphon jet. That's one way to do it I guess. I have seen this on certain power versions on bowls that have used pumps before, but not on a gravity bowl before.
Wait for it.
That bulge covers the siphon jet tubing.
The fitting from the tank, going off to the left within the bulge.
And finally, connected to the siphon jet on the underside of the bowl.
Wait for it.
That bulge covers the siphon jet tubing.
The fitting from the tank, going off to the left within the bulge.
And finally, connected to the siphon jet on the underside of the bowl.