Anchor Line Failure

So... How do you think this anchor line failed....
It's definitely not your typical three strand anchor line...
Click on the picture to see larger version.

I'll be obtaining the West Marine econo pack 150 foot of three strand 1/2" anchor line, then shackling to a 10 foot length of 5/16" (hot dipped galvanized steel) proof coil chain... which I then need to shackle to a new anchor... the anchor I lost was a nice Bruce... WM doesn't seem to sell those, but they do have a "Bruce-like" claw anchor...