when typing in some `projectile` filter string for instance (eg `SPC p f`) in `spacemacs`, I often would like to reuse the word under the cursor.

I know about `C-y` to paste. Which is the one to insert the word under the cursor? I stumbled on `C-w` but it's not that. And why does `C-w` does by the way??

(btw if there is something more `spacemacs`-y I'm interested)