You had to squeeze this block really hard to make it break. That's because concrete and steel are both very strong in compression. It was hard to pull this concrete block apart because the steel bars inside make it very strong in tension. That's why some of the tallest skyscrapers in the world are made of reinforced concrete. It wasn't easy for you to squeeze this cast-iron block.
Cast iron is strong in compression.
That's why early arch bridges were made of cast iron. It was easy for you to pull this cast-iron block apart. You had to push extra hard on this steel block to make it bend and break. Steel is stronger than any other material in compression. That's why engineers choose steel beams and columns to support most skyscrapers.