objects/basic/red_block/red_block.urdf

<?xml version="1.0"?>
<robot name="red_block">
  <link name="base_link">
    <visual>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <mesh filename="red_block.obj" scale="1 1 1"/>
      </geometry>
    </visual>
    <collision>
      <origin xyz="0.000000 0.000000 0.000000" rpy="0.000000 0.000000 0.000000"/>
      <geometry>
        <mesh filename="red_block.obj" scale="1 1 1"/>
      </geometry>
    </collision>
    <inertial>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <mass value="0.051853"/>
      <inertia ixx="0.00001909" ixy="0" ixz="0" iyy="0.00001909" iyz="0" izz="0.00001909"/>
    </inertial>
  </link>
</robot>