Several years ago, one of these mysterious pod piles materialized seemingly overnight in my bathroom (warning: BIG ASS FILE—I left it non-resized in case anybody needs to examine detail). Now there’s another one. I think it’s in the exact same place. The floor casing behind it is 1 ¼" , so the pile is perhaps ¾". Note how it appears to be spilling out of a nail hole in the casing—*or is that a nail hole *(cue in creepy music…)? What in the name of all that is holy is setting up housekeeping there? It sure doesn’t look like termite detritus, but that’s the only thing I can think of. Ants are a huge problem in my neighborhood, but I haven’t seen many lately. It’s been there about two weeks or so, I think, if that helps.
To me, those look like seeds. If so, I’d suspect you have a mouse or something similar that’s trying to store goodies away for the winter.
Set up mousetraps first, look towards carpenter ants/bees/termites later. Or alternately, hire a pro exterminator to identify this accumulation of whatever it is.
Almost looks like grainy brown mustard seeds.
They look like feces to me. But I’m not sure whose.
Wow, you sure are lucky to have those termites keeping the ants at bay. 
Yep, that’s exactly what it is. I Googled up other pics and they look exactly like what’s on my bathroom floor, right down to the hexagonal shape and the two pit-shaped indentations on each pellet. Far be it from me to second-guess the Creator, but that’s a hell of a way to design a poop. I would have sworn they were mustard seeds myself. Drat. Well, at least I don’t have to catch a mouse.
Termites: the best argument ever for renting.
No, just several thousand termites.
gnawgnawgnawgnaw