I might be nitpicking, but I'm not sure that's necessarily true. You could in theory write a compiler for a new language in C (or even assembly!), and once you have a working language, re-write the compiler in that new language. Now that there is no C code involved in the stack anymore, would that still count as a C-turtle?
Haskell for example, has some "bits" written in C, but a lot is written in Haskell or assembly[1]. So if you look at the WHOLE stack you'll find C _somewhere_ (probably most places), but I don't think _everything_ boils down to C.
Granted, a LOT of stuff is written on top of C.
[1] https://stackoverflow.com/questions/23912375/what-language-i...