Jeff Wiseman wrote in message ...
Sounds like it was there to prevent 3-year-olds from rolling
marbles into the port opening :-)

Once they are in there, just try removing them!

:-) :-)

Pardon me I, just cannot resist telling you about my grandfather who
had a glass bottle made for vodka. It had a flat top with the
bottleneck rising from that. For some reason the top was not perfectly
flat, but had sunk down a bit at the neck, which made it completely
impossible to pour the last drop out of the bottle.
I don't think he used that bottle very much... :-)