Soft Rock / a rubber door stop

The door stop now always with the triangle form and use the angle to stop the door,
but it really hard to pull it out from the seam gap of door.
This concept use different material feature to make a new form door stop,
this hollow, elasticity and soft rubber can stop the door easily,
and it's just like a small white rock under your door.
Every time when you want to move the door stop, you just tread it to flat and pull it out.