When Habelia optata first skittered into public consciousness more than a century ago, scientists didn’t know what to make of it. The long-extinct sea predator, which flourished during the middle Cambrian period about 508 million years ago, measured less than a inch long, yet it wasn’t an animal you’d be keen to encounter.
“Tiny yet exceptional fierce,” according to paleontologists, H. optata sported an extensive tail, jointed limbs, and a peculiar, helmet-like head that housed several pairs of appendages for feeling, grasping, and pulverizing prey—even those with hard carapaces, like trilobites.