COBOL is another one. COBOL programs written decades ago are still running unchanged on mainframes today. (Not that it was ever used for scientific computing.)
Relevant to Fortran, there's a version of ESSL that I recall on OS\370 now for POWER9 (and doubtless 10). Scientific subroutine libraries are arguably the best example of the re-use beloved of those who haven't seen their OOP code last decades.
My bad, the 21 years difference must be important (somehow?)