The muscle fibers of squid and octopus are extremely thin—less than a tenth the diameter of a typical fiber in a fish or steer (0.004 mm, vs. 0.05–0.1 mm)—which makes the flesh dense and fine-textured. They’re arrayed in multiple layers, and greatly reinforced with strengthening and toughening connective-tissue collagen, some three to five times more than fish muscle has. Unlike the fragile collagen of fish, squid and octopus collagen is extensively cross-linked and behaves more like the collagen of meat animals.