diff --git a/game/state/planet.hpp b/game/state/planet.hpp
index 0407683..38f02b6 100644
--- a/game/state/planet.hpp
+++ b/game/state/planet.hpp
@@ -2,11 +2,38 @@
 
 #include "object.hpp"
 
+#include <cstdlib>
+
 namespace game {
     class Planet : public Object {
     public:
-        Planet(const glm::vec2 &pos, float r) : Object(pos, r)
+        /**
+         * Planets are build out of one material.
+         * TODO: support mixture or multiple material per planet.
+         */
+        enum class Material {
+            Rock,
+            Metal,
+            Sand,
+            Gas,
+            Ice,
+            Water,
+            Sun
+        };
+
+        Planet(const glm::vec2 &pos, float r) : Planet(pos, r, Material::Rock)
         {
         }
+
+        Planet(const glm::vec2 &pos, float r, Material mat)
+            : Object(pos, r)
+            , material(mat)
+            , seed(rand())
+        {
+        }
+
+        // nice for rendering attributes
+        Material material;
+        int      seed;
     };
 }