Mass-radius diagram for Wolf 327b (red star) and known transiting planets with mass determinations with a precision better than 30% (parameters taken from the TEPcat database; Southworth 2011). Planets orbiting M-type stars (T_eff ≤ 4000 K) are marked with circles, orange indicate planets with periods P > 1 day, and red circles indicate USP planets (P ≤ 1 day) around M dwarfs. The lines in the mass–-radius diagram represent the composition models of Zeng et al. (2016, 2019) for planets with pure iron cores (100% Fe, solid brown line), Earth-like rocky compositions (32.5% Fe plus 67.5% MgSiO₃, dashed green line) and pure rock (100% MgSiO₃, dash-dotted purple line).