Mass-radius diagram of well-characterized planets with radii R < 3 R_⊕ and masses M < 10 M_⊕. All the planets plotted in gray are planets transiting M dwarfs taken from Trifonov et al. (2021), last updated on 08 April 2021, with AM < 20% and AR < 20%. The “p Earth” is the constant Earth-density line. TOI-1468b and c are marked with red and blue stars, respectively, and LTT3780b;c, L231-32b;c;d, and TOI1749b;c;d are marked with salmon filled circles, inverted triangles and squares, respectively. Theoretical mass-radius relations are taken from Zeng et al. (2019).