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In the Iridium layer, at Chicxulub, it's not all that thick. It's 0.4 to 0.6 inches thick. So what a vast, almost an inch thick, so one about two centimeters, it's not all that thick. So it's a very thin layer all around the world. And it's not common, it's really not common in the Earth's crust, but very common in asteroids and the proportion that you find in asteroids matches what would be seen in the crust in this small layer, which is how we put two and two together and extrapolate and say, yes, it was from this impactor 66 years ago.