[citation needed] Like other heterostracan fishes, Pteraspis had a protective armored plating covering the front of its body.

Though lacking fins other than its lobed tail, it is thought to have been a good swimmer due to stiff, wing-like protrusions derived from the armoured plates over its gills.

This, along with the horn-like rostrum, made Pteraspis very streamlined in shape, which is good for swimming.

Pteraspis also had some stiff spikes on its back, possibly an additional form of protection against predators.

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