Crystallized DEF nest?

Guys, I went this morning to the truck to get ready to leave on a trip, and I came across this underneath the truck on the driver side. My truck had issues with regens last tour out. I was out for 9 days and it asked for 4 parked regens. And it's using more DEF than usual. MPG and pulling power are fine.

But we won't get into the mechanical issues here. I'll leave that for another thread. Anyway, I came across this. At first, I thought it was a small mound of crystallized DEF, because of the aforementioned problems and the fact that this "thing" was underneath the driver side in the vicinity of the DEF tank. But as I drove and thought more about it, I thought it might be some sort of nest. I thought this because of the hole on the top and the symmetry of the structure.

What do you guys think? My truck yard is basically in the desert. I know some of you older and rural types might be able to tell if it's some sort of critter.

 

So, I'm pretty sure it's a DEF leak. I drained the DEF about a month ago and changed the gasket in the drain plug. I also changed the DEF filter. Maybe I left something loose.

 

Yeah, that's what the consensus is. I thought that at first, but what gave me pause was the artistic look of it. As if it was done by design. So that's when I thought it was maybe some desert creature like a tarantula or something.

 

Yeah, maybe we have some DEF-spitting snakes or lizards. But that little crystallized DEF tower was kind of weird, and I know some ants make mounds and such, and some spiders build some interesting nests. So, I thought maybe it was possible that it was a desert creature. I've never seen DEF do that, but I guess I learned something new.

 

Okay folks, I think I found the leak. It seems to be the drain plug of the DEF tank. Do you guys concur? So, my question: Would this have caused the frequent regens and the code SPN 5394 FMI 17?

[SPN 5394 FMI 17 is a heavy-duty truck diagnostic code indicating an issue with the Selective Catalytic Reduction (SCR) or Diesel Exhaust Fluid (DEF) dosing system. Specifically, FMI 17 means the data is valid but below the normal operating range, often pointing to low DEF pressure, a clogged/stuck dosing valve, or insufficient NOx conversion.]

There was a new DEF stalagmite under the truck this morning. The drain plug was right above it. Here are two pics.

 

Yes, there was crystallization where you circled the plug. But I scraped it off to get a better look. I changed the DEF filter myself about 4000 miles ago. When I did this, I also drained the DEF tank, changed the gasket around that plug, and changed the funnel filter. I must have left that bolt loose, or maybe I jumped the thread in the plug. That has to be it because all the problems started during the trip immediately after I did the maintenance. I'm thinking the code came on because the leak caused weaker pressure in the pump? What do you think?