This is a video of the knife swinging tentacle that Youtuber outaspaceman built. It is basically the exact reason why humanity doesn't deserve to continue. If I could summon a meteor with my brain I would do it in a heartbeat. A HUMMINGBIRD'S heartbeat. You know what? I'm gonna do it. *strains so hard I shit my pants* Uh-oh. Somebody call my mom, she'll know what to do.
Keep going for the video, but skip to 0:35 if you just want to see the stabbing.
Thanks to Pattern, who allegedly saw an octopus stab a clam once.