An extinct group of armored fish from ancient seas that had jointed armor plates covering their bodies instead of scales.
From Greek 'arthro-' meaning joint and 'dira' meaning fearful or terrible. The name refers to the distinctive jointed armor that characterized these Paleozoic fish.
These 400-million-year-old fish were basically the tanks of their time—they had sophisticated jaws with bone instead of teeth, and some grew as large as great white sharks, making them apex predators before dinosaurs even existed!
Complete word intelligence in one call. Free tier — 50 lookups/day.