Results of the internal structure analysis for TOI-238 b. Depicted are the posterior distributions for the mass fractions of the inner core, the mantle and the volatile layer with respect to the whole planet, as well as the water mass fraction in the volatile layer, Z_envelope (from left to right). The top row (case A) was generated for a prior that would be in agreement with a water-rich composition, e.g. if the planet formed outside the iceline, while the bottom row (case B) assumes that water was not readily available for accretion during planet formation. The three colours depict different assumptions for the planetary Si/Mg/Fe ratios: stellar (purple), iron-enriched (pink), and uniformly sampled without considering the stellar ratios (blue). The vertical dashed lines show the median of each distribution, while the dotted lines show the respective priors.