<mujocoinclude>
 <worldbody>
  <body name="box" pos="0.5 0 0">
   <freejoint name="box:joint"/>
   <geom condim="4" name="box:geom1" pos="0 0 0" rgba="0.32 0.32 0.32 1" size="0.02 0.02 0.02" solimp="0.99 0.99 0.001"
         solref="0.002 0.1" type="box" density="500"/>
  </body>
 </worldbody>
</mujocoinclude>