How to use ontriggerEnter and still collide with terrain

Ok I have a sphere which has no rigid body, it has a sphere collider set to istrigger=true;
I tried giving it rigid body and stuff (with gravity off) but it stills passes through terrain spikes …I want it to collide with it.

The terrain comes with terrain collider (the floor part works, the spikes don’t)

Is there a way to fix it so the sphere collides with terrain spikes?

this is the code I am using for the sphere to move (only the update part):

 //  rotate towards the target
            myTransform.rotation = Quaternion.Slerp(myTransform.rotation,Quaternion.LookRotation(target.position-myTransform.position),rotationSpeed*Time.deltaTime);
      //  move towards the target:
            Debug.Log("moving towards target");
           myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;

What it does is goes from 1 point to another each represented as current target.
so what I did was placing them so the spike is in the middle.

You should use the OnCollisionEnter() by uncheck the IsTrigger, as IsTrigger is to just detect collision between two object but object will not be under the effect of collision.