diff --git a/oscope-sphere/bin/data/shaders/sphere.frag b/oscope-sphere/bin/data/shaders/sphere.frag
index e22ab9d..85e76f4 100644
--- a/oscope-sphere/bin/data/shaders/sphere.frag
+++ b/oscope-sphere/bin/data/shaders/sphere.frag
@@ -3,7 +3,8 @@
 uniform sampler2D spectroTex;   // width = time, height = freq, R32F [0,1]
 uniform float scrollOffset;
 uniform int   colormapId;
-uniform int   renderMode;       // 0 = skin, 1 = points
+uniform int   renderMode;       // 0 = skin, 1 = points, 2 = wireframe
+uniform vec4  shellTint;        // rgb tint + alpha for wireframe / shells
 
 in vec2  vSphereUV;
 in vec3  vViewPos;
@@ -47,8 +48,9 @@ void main() {
     }
 
     if (renderMode == 2) {
-        // wireframe: bright unlit colormap lines
-        fragColor = vec4(col * 1.4 + vec3(0.06), 1.0);
+        // wireframe / concentric shells: bright lines, tinted per draw
+        vec3 wc = (col * 1.4 + vec3(0.06)) * shellTint.rgb;
+        fragColor = vec4(wc, shellTint.a);
         return;
     }
 
diff --git a/oscope-sphere/src/SphereViz.cpp b/oscope-sphere/src/SphereViz.cpp
index cba09d6..208ed73 100644
--- a/oscope-sphere/src/SphereViz.cpp
+++ b/oscope-sphere/src/SphereViz.cpp
@@ -99,10 +99,41 @@ void SphereViz::drawPoints() {
     shader_.end();
 }
 
-void SphereViz::drawWireframe() {
+void SphereViz::drawWireMesh(const ofFloatColor& tint) {
     shader_.begin();
     bindUniforms();
     shader_.setUniform1i("renderMode", 2);
+    shader_.setUniform4f("shellTint", tint.r, tint.g, tint.b, tint.a);
     mesh_.drawWireframe();
     shader_.end();
 }
+
+void SphereViz::drawWireframe() {
+    drawWireMesh(ofFloatColor(1.0f, 1.0f, 1.0f, 1.0f));
+}
+
+void SphereViz::drawShells(float t, float bass, float kick) {
+    ofDisableDepthTest();
+    ofEnableBlendMode(OF_BLENDMODE_ADD);
+
+    // outer shell: larger, counter-spinning, blue, breathes with bass
+    ofPushMatrix();
+    ofRotateYDeg(-t * 23.0f);
+    ofRotateXDeg( t * 14.0f);
+    const float so = 1.40f + bass * 0.25f;
+    ofScale(so, so, so);
+    drawWireMesh(ofFloatColor(0.28f, 0.62f, 1.00f, 0.55f));
+    ofPopMatrix();
+
+    // inner shell: smaller, opposite spin, magenta, pulses with kick
+    ofPushMatrix();
+    ofRotateYDeg( t * 34.0f);
+    ofRotateXDeg(-t * 23.0f);
+    const float si = 0.62f + kick * 0.30f;
+    ofScale(si, si, si);
+    drawWireMesh(ofFloatColor(1.00f, 0.42f, 0.80f, 0.60f));
+    ofPopMatrix();
+
+    ofDisableBlendMode();
+    ofEnableDepthTest();
+}
diff --git a/oscope-sphere/src/SphereViz.h b/oscope-sphere/src/SphereViz.h
index a0c6e69..91b484d 100644
--- a/oscope-sphere/src/SphereViz.h
+++ b/oscope-sphere/src/SphereViz.h
@@ -20,10 +20,12 @@ public:
     void drawSkin();
     void drawPoints();
     void drawWireframe();
+    void drawShells(float time, float bass, float kick);
     void setColormap(int id) { colormapId_ = id; }
 
 private:
     void bindUniforms();
+    void drawWireMesh(const ofFloatColor& tint);
 
     std::unique_ptr<oscope::SpectrogramBuffer> spectro_;
     ofVboMesh     mesh_;
diff --git a/oscope-sphere/src/ofApp.cpp b/oscope-sphere/src/ofApp.cpp
index 119a695..ab5e22e 100644
--- a/oscope-sphere/src/ofApp.cpp
+++ b/oscope-sphere/src/ofApp.cpp
@@ -56,6 +56,8 @@ void ofApp::update() {
     if (!ofGetMousePressed())
         spin_ += (8.0f + 80.0f * energy) * dt;
     pulse_ += (1.0f + 0.20f * kick - pulse_) * 0.25f;
+    bass_ = 0.5f * (b1.bass + b2.bass);
+    kick_ = kick;
 
     sphere_.setColormap(colormap_);
     sphere_.pushSpectrogramColumn(analyzerCh1_.magDown(),
@@ -74,6 +76,7 @@ void ofApp::draw() {
     if (layerA_) sphere_.drawSkin();
     if (layerD_) sphere_.drawWireframe();
     if (layerC_) sphere_.drawPoints();
+    if (layerE_) sphere_.drawShells(t, bass_, kick_);
     if (layerB_) rings_.draw();
     ofPopMatrix();
     cam_.end();
@@ -88,6 +91,7 @@ void ofApp::drawHud() {
     hud += std::string("[2] rings  ") + (layerB_ ? "on" : "off") + "\n";
     hud += std::string("[3] points ") + (layerC_ ? "on" : "off") + "\n";
     hud += std::string("[4] wire   ") + (layerD_ ? "on" : "off") + "\n";
+    hud += std::string("[5] shells ") + (layerE_ ? "on" : "off") + "\n";
     hud += std::string("[c] colormap   [space] ") +
            (frozen_ ? "frozen" : "live");
     ofDrawBitmapString(hud, 16, 24);
@@ -100,6 +104,7 @@ void ofApp::keyPressed(int key) {
         case '2': layerB_ = !layerB_; break;
         case '3': layerC_ = !layerC_; break;
         case '4': layerD_ = !layerD_; break;
+        case '5': layerE_ = !layerE_; break;
         case 'c':
         case 'C': colormap_ = (colormap_ + 1) % 2; break;
         case ' ': frozen_ = !frozen_; break;
diff --git a/oscope-sphere/src/ofApp.h b/oscope-sphere/src/ofApp.h
index c74a06d..d7d55ec 100644
--- a/oscope-sphere/src/ofApp.h
+++ b/oscope-sphere/src/ofApp.h
@@ -36,9 +36,12 @@ private:
     bool  layerB_   = true;
     bool  layerC_   = true;
     bool  layerD_   = true;
+    bool  layerE_   = true;
     int   colormap_ = 0;
     float scopeSr_  = 16.0e6f;
     float spin_     = 0.0f;
     float pulse_    = 1.0f;
+    float bass_     = 0.0f;
+    float kick_     = 0.0f;
     std::string statusText_;
 };