tokens: structure than in the spot. Moreover, the smearing due to the point-spread function of the telescope may dilute into the bright structure part of the magnetic signal belonging to the surrounding umbra and penumbral filaments. However, the average estimated errors for the vertical and horizontal component of the field in the structure are about ±35 G and ±70 G, respectively. Thus, the strong horizontal field of about 2000 G appears to be a robust result. The presence of such a significant horizontal component of the magnetic field allows us to exclude the field-free configuration typically observed in LBs. Conversely, it supports the possibility that the magnetic field of the flux rope forming the filaments around the sunspot may have a counterpart in the middle of the sunspot umbra, where it appears to end in the cospatial chromospheric images. This would also provide an explanation for the detection of opposite polarity in the structure with respect to the umbra, as well as an alternative interpretation for the opposite polarity of an apparently filamentary LB with respect to its hosting umbra observed by Bharti et al. ( 2007 ). Note that this phenomenon is different from the magnetic reversals found by Lagg et al. ( 2014 ) and Felipe et al. ( 2016 ) in LBs, due to the bending of the field lines along the atmospheric stratification of the structure. Moreover, this scenario is confirmed by the portions of the bright feature characterized by both upward and downward plasma motions along it, which are compatible with plasma flows along the helical field lines of a flux rope. Actually, the length of each portion of the filamentary structure with coherent plasma motion is of about 5′′, which could correspond to the pitch of a helically twisted flux tube. Therefore, we guess that this bright filamentary structure is not a filamentary LB, but it is due to the accumulation of plasma coming from higher solar atmospheric levels into the photosphere. The presence of stably inclined fields belonging to the flux rope, which are touching part of the sunspot umbra, would set in radiatively driven penumbral magneto-convective mode (Jurčák et al. 2014 , 2017 ). Indeed, high-resolution observations have shown that plasma fallen from chromospheric layers can lead to the formation of penumbra in sunspots (Shimizu et al. 2012 ; Romano et al. 2013 , 2014 ). Furthermore, penumbral-like structures, i.e., so-called orphan penumbrae, have been reported as a photospheric counterpart of a chromospheric filament (Kuckein et al. 2012a , 2012b ; Buehler et al. 2016 ). Observations of similar bright filaments inside the umbra, called UFs, have been recently reported by Kleint Sainz Dalda ( 2013 ). They found that UFs were characterized by a horizontal flow opposite to the Evershed flow and they also found from coronal images the presence of bright coronal loops that seemed to end in UFs. To interpret such phenomena, Kleint Sainz Dalda ( 2013 ) conjectured two different
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