Miniature grenades? Fishing lures? Broken screws? Nope: these are in fact a new kind of medical implant that could help your ruptured tendons recover.
Usually, ruptured tendons are repaired by implanting bone anchors made from titanium that allow the breakage to heal; the titanium studs have to be removed afterwards. These new implants are made from iron-tricalcium phosphate though which, even though made from metal and ceramic, is biodegradable. Over two years they simply break down into your body. The ceramic components even stimulate bone growth, to encourage your body to fill the hole they leave behind. Not that any of that will make rupturing a tendon any less painful. [Fraunhofer Institute via New Scientist]