subsurface

A metallic-roughness surface that also transports light beneath itself, for skin, foliage, wax, marble and thin fabric.

Set subsurface_color to the tint of the light that scatters through; leaving it black makes this a plain metallic-rough surface. subsurface_radius sets how far light spreads beneath — larger values wrap the shading further past the terminator, and reach further in whichever channels the colour is strongest in.

thickness (and thickness_texture) control how readily a backlit surface glows. Thin geometry transmits; thick geometry stays solid.

Both effects are evaluated in the engine's light loop, so they are shadowed and attenuated like every other lobe.