That’s not the standard rule for improvised weapon damage. It’s a good rule, it’s the one I use, but it’s not the standard rule.I'd consider it an improvised weapon. It's definitely not designed as a weapon, but could be used as one. As for damage, I'd use the standard rules: if you can use it with only one hand, it's 1d4, but a larger one would be 1d6.
Like others, improvised.Born from a discussion amongst friends, would you consider a rock to be an improvised weapon or a simple weapon?
If the latter, would you rule differently depending on the size of the rock? Sling stone vs club sized vs stone giant rock for example.
Yup, this exactly. If you just grab a rock off the ground, that's improvised. If you take a little time to pick one that's suited for throwing, I'd call it a simple weapon doing 1d4 with a range of maybe 10/30. (I wouldn't make it less than 1d4, since that is standard improvised weapon damage; the short range is what makes it inferior to a sling or even a thrown dagger.)Depends I’d consider a random rock to be improvised on the basis that its not balanced for throwing, or hitting things with.
However I’d allow a character to use a polished ‘balanced’ throwing rock as a simple weapon, especially if they had a culture/habit of rock throwing (like giants hurling boulders or halflings skipping stones)