Living about 300 million years ago, the Arthropleura is the largest arthropod (a classification that includes insects, spiders, and crabs) known to have existed. It resembled a giant millipede, with the weight of a large dog and the length of a small car.

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Big Bugs and Colossal Crabs: 7 Invertebrates of Unusual Size

We’re not talking about obese bureaucrats here. The creatures on this list literally lack spinal columns…and yet attain relatively massive proportions. Before you reach for the bug spray, consider this: despite their startling gigantism, none of these organisms are harmful to humans (unless unduly