The extinct shark Edestus used its teeth like saw blades, sliding them past each other like a power tool to slice through the soft flesh of its prey
Source:
https://www.newscientist.com/article/2230366-ancient-shark-used-its-teeth-like-the-blade-of-a-power-tool/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home