“Their wide-open mouth, armed with transparent, saber-like teeth, effectively disappear in the surrounding blackness,” said Dr. Webb.

The Goliath Power Saber is the first self-retracting and extending lightsaber toy — and it was nearly an official Star Wars product.

Saber teeth took this tradeoff to the extreme, Rayfield and her colleagues report in Current Biology, becoming about as good as they could be at puncturing prey, ultimately sacrificing durability.