  We present the discovery of a very extended (550 kpc) and
low-surface-brightness ($ 3.3 \mu \mathrm{Jy} \, arcsec^{-2} $ at 144 MHz)
radio emission region in Abell 1318. These properties are consistent with its
characterisation as an active galactic nucleus (AGN) remnant radio plasma,
based on its morphology and radio spectral properties. We performed a
broad-band (54 - 1400 MHz) radio spectral index and curvature analysis using
LOFAR, uGMRT, and WSRT-APERTIF data. We also derived the radiative age of the
detected emission, estimating a maximum age of 250 Myr. The morphology of the
source is remarkably intriguing, with two larger, oval-shaped components and a
thinner, elongated, and filamentary structure in between, plausibly reminiscent
of two aged lobes and a jet. Based on archival {\it Swift} as well as SDSS data
we performed an X-ray and optical characterisation of the system, whose virial
mass was estimated to be $ \sim 7.4 \times 10^{13} \, \mathrm{M} _{\odot}$.
This places A1318 in the galaxy group regime. Interestingly, the radio source
does not have a clear optical counterpart embedded in it, thus, we propose that
it is most likely an unusual AGN remnant of previous episode(s) of activity of
the AGN hosted by the brightest group galaxy ($ \sim 2.6 \times 10^{12} \,
\mathrm{M} _{\odot}$), which is located at a projected distance of $\sim$170
kpc in the current epoch. This relatively high offset may be a result of IGrM
sloshing sourced by a minor merger. The filamentary morphology of the source
may suggest that the remnant plasma has been perturbed by the system dynamics,
however, only future deeper X-ray observations will be able to address this
question.
