Terrano uses nuclear-spin comagnetometers (e.g. He/Xe) and precision spin-precession to search for exotic spin-dependent forces, dark matter and electric dipole moments. This vapour-phase approach reaches femto-to-picotesla sensitivities complementary to NV-center diamond ensemble quantum sensors (DEER, nano-NMR, T1 relaxometry) that operate near the pT/sqrt(Hz) regime.