/usr/lib/x86_64-linux-gnu/pkgconfig/sphere.pc is in libsphere-dev 3.2-3build2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 | prefix=/usr
exec_prefix=${prefix}
libdir=/usr/lib/x86_64-linux-gnu
Name: sphere
Description: Spherical operators for geophysics
Version: 3.2
Libs: -L${libdir} -lsphere
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