What’s wrong with the bottom of my egg?

After a weekend cook, I noticed a ton of stuff on the pavement underneath my egg.

I did an indirect cook for a few hours (3 hours at 220) and then cranked it to 500 for another 30 minutes. This is pretty typical for how I use my XL egg.

I took this photo of the underside. While it does look like there's a tiny crack, all that gunk appears to just be coming through the ceramic rather than seeping through the crack and then spreading.

What is going on with it?

Also a photo of the stuff that dripped on the pavement under the egg.