A newspaper website headline in Australia says that the volcano in Hawaii is spewing rocks the size of microwaves. How big (or small) is that? 1 metre to 1 millimetre. A one-millimetre rock is not a rock. The first paragraph of the story then says ‘boulders the size of small cars’, which are presumably the size of radio waves.
That said, I wouldn’t want to be landed on by a one-metre rock spewed from a volcano.
[update 27 May: I saw a headline from a US paper which referred to ‘fridge-sized boulders’, so maybe the Australian headline referred to microwave ovens, not microwave radiation. There’s a difference in size between a microwave oven, a fridge and a small car.]