mujoco

<mujoco model="Box mesh with multiccd">
  <option>
    <flag multiccd="enable"/>
  </option>

  <asset>
    <mesh name="box"
          vertex="-1 -1 -1
                   1 -1 -1
                   1  1 -1
                   1  1  1
                   1 -1  1
                  -1  1 -1
                  -1  1  1
                  -1 -1  1"/>
  </asset>

  <worldbody>
    <geom pos="0 0 -1" type="box" size="5 5 1"/>
    <body pos="0 0 0.9999">
      <freejoint/>
      <geom type="mesh" mesh="box"/>
    </body>
  </worldbody>
</mujoco>