Hi Botani. Something partially penetrated and slit the tread. I would recommend you go to the tire shop that mounted and installed the tires and speak to them about this.
If I recall correctly, you have pretty high temperatures where you live and like to drive at high speeds? Tire damage is nothing to fool around with, and getting random advice from anonymous Internet strangers (including me) is not the best way to protect your safety. We can not inspect it, determine how deep that cut is, etc. etc.
Therefore, it would be best for you to have a tire shop inspect and advise you on whether that tire is safe to drive on, or if it needs replacement.
Perhaps that set of tires even has some sort of Road Hazard Warranty?
Let us know how you make out and good luck.