Mass–density distribution of transiting BDs and low-mass stars, depicting systems with precision >20% in both mass and density (e.g., C. M. Persson et al. 2019). BDs are shown as circles, color coded by equilibrium temperature (T_eq) and with marker size scaled by radius, while low-mass stars are shown as star symbols with the same color coding. The shaded regions indicate the approximate transition regimes corresponding to the deuterium-burning limit (∼11–16.3 M_J; D. S. Spiegel et al. 2011) and the hydrogen-burning boundary (∼66–81.7 M_J; C. V. Morley et al. 2024). The distribution exhibits a turnover in density around ∼60–70 M_J. TOI-2155 b is highlighted with a red “X” over its marker, annotated for emphasis.