/usr/lib/x86_64-linux-gnu/libField3D.so.1.6 is in libfield3d1.6 1.6.1-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libField3D.so.1.6.1
/usr/lib/x86_64-linux-gnu/libField3D.so.1.6.1