A landmine perhaps?

I most likely ran over some sharp metallic road debris going downhill/ at a high rate of speed on a previous ride which I most likely noticed but shrugged off as nothing. Unfortunately, this was a mortal wound to the tire sidewall. Then I kept riding with this unbeknownst to me, until a blowout such as this, happened sooner or later.

Being a commuter, I ride in and out on it everyday and aside from checking up on the pressure, chain wear, and minor adjustments to the drivetrain; I did't really think about looking over the "bulletproof" tires until I start getting recurring pinhole flats.