Caltrops are tetrahedral items used for making ground hard to cover. They always land with a pointy bit sticking up. Handy for preventing pursuers from catching you, whether they are on foot, on horseback, or, in more modern cases, in a vehicle.
Caltrops video games (Tools theme)
Character Suggestion - A martial artist/ninja like character that utilises futuristic weapons - Game Suggestions & Feedback - Killer Instinct Forums
Origin of movie trope where impaled character pulls/pushes blade/spear further into body? - Movies & TV Stack Exchange
Acquisitions Incorporated - Flip eBook Pages 51-100
Television KamenSentai
caltrops press — FEEDBACK LOOP #12: AJ Suede's Most Black
Twelve Red Lines (a One Piece SI fanfic), Page 10
Sea Hurtchin - TV Tropes
Caltrop - Alchetron, The Free Social Encyclopedia
Caltrops - TV Tropes