What is this domestic freakery (includes images, possibly of small dead things)

[Nowdecide]

This debris is on our bedroom window sill. I clear it away, more arrives, within a day.

I suspect ants. Maybe down between the sill and bit at the back?

Can anyone identify it and/or suggest a remedy?

I've never seen the like.

We had this, I think it was shell casings (?) from some sort of insect. We siliconed up the brickwork from the corner of the windowsill it was piling up in.

Ah, thank you justdontevenfuckingstart (nice, if scary name, btw, respect) so you think they come from outside? Hmmm. Interesting.

Had it at work too, came through the brickwork. Never actually saw any creepies.

Bit odd as the garden is outside - and the ground is level with the bottom of the window. So no wall beneath window (there is but it's earth under the garden against wall if you see what I mean) so no exposed brickwork externally.
Could they be inside the wall?!

Carpenter ants! Found more detail based on your replies. Looks like we have an infestation. . .

Yes the debris we had was exactly the same when I googled.