Shells (helmet and stone)

Overlays on normal moles: a helmet needs two BONKs, a stone only breaks under your own hammer.

From the middle of a show some normal moles appear with a shell. They are still normal moles for every piece that counts normals.

HELMET: the first BONK of any kind only cracks it; the second one pops the mole. STONE: chains, blasts, projectiles and echoes only bounce off (tink); the hammer's own strike on its hole (or an extra hammer-module BONK in the strike row) shatters it and pops the mole at once.

A refused or cracking hit pays nothing: no score, XP, Audience, Momentum or chain link. Shells keep a build that chains everything from winning while standing still.