https://threadreaderapp.com/thread/1362557149147058178.html
(Many thanks to Elon for making it impossible to read more than the first tweet on x.com without an account...)
Very unlikely to occur in nature I guess :-)
Sometimes to innovate you have to think like a child — or a teenager.
If an iceberg is currently floating in a vertical orientation where more of it's mass to one side of it's center of gravity (bottom half) is underwater compared to the mass on the other side (top half), then it's going to tend to rotate until both sides are equally above water, so (depending on mass distribution) horizontal orientations are likely to win over vertical ones.
Of course an iceberg could balance vertically, but that's like balancing a pencil on your finger - not the most stable, and any disturbance (such as the initial calving event) is likely to rotate it into a more stable horizontal orientation.