Bubbling Mud Pool

A bubbling mud pool: a round pool 2.5 x 2.5 m of thick grey-brown mud inside a low 0.15 m cracked clay rim, flat base at y=0, the mud surface modelled with shallow swells, bubble domes and burst rings; the mud is its own zone, no tone.

风格：low-poly, flat-shaded vertex colors, no textures, 2 materials: the shared opaque one plus a distinct surface (glass, water or chrome), which stays its own mesh through mergeAssets rather than merging into the rest; shares palette and scale with its kit