diff --git a/rtchallenge/src/materials.rs b/rtchallenge/src/materials.rs
index a18e80f..cbcbfb3 100644
--- a/rtchallenge/src/materials.rs
+++ b/rtchallenge/src/materials.rs
@@ -1,5 +1,5 @@
 use crate::tuples::Color;
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Clone)]
 pub struct Material {
     pub color: Color,
     pub ambient: f32,
diff --git a/rtchallenge/src/spheres.rs b/rtchallenge/src/spheres.rs
index ca3e0db..0888a89 100644
--- a/rtchallenge/src/spheres.rs
+++ b/rtchallenge/src/spheres.rs
@@ -1,9 +1,9 @@
 use crate::{
     intersections::{Intersection, Intersections},
+    materials::Material,
     matrices::Matrix4x4,
     rays::Ray,
     tuples::{dot, Tuple},
-    EPSILON,
 };
 
 #[derive(Debug, PartialEq)]
@@ -11,12 +11,13 @@ use crate::{
 pub struct Sphere {
     // TODO(wathiede): cache inverse to speed up intersect.
     pub transform: Matrix4x4,
+    pub material: Material,
 }
 
 impl Default for Sphere {
     /// # Examples
     /// ```
-    /// use rtchallenge::{matrices::Matrix4x4, spheres::Sphere};
+    /// use rtchallenge::{materials::Material, matrices::Matrix4x4, spheres::Sphere};
     ///
     /// // A sphere's default transform is the identity matrix.
     /// let s = Sphere::default();
@@ -27,10 +28,21 @@ impl Default for Sphere {
     /// let t = Matrix4x4::translation(2., 3., 4.);
     /// s.transform = t.clone();
     /// assert_eq!(s.transform, t);
+    ///
+    /// // Default Sphere has the default material.
+    /// assert_eq!(s.material, Material::default());
+    /// // It can be overridden.
+    /// let mut s = Sphere::default();
+    /// let mut m = Material::default();
+    /// m.ambient = 1.;
+    /// s.material = m.clone();
+    /// assert_eq!(s.material, m);
+
     /// ```
     fn default() -> Sphere {
         Sphere {
             transform: Matrix4x4::identity(),
+            material: Material::default(),
         }
     }
 }