Character Falls Through Blender Made Floor

I'm pretty much a noob at all of this, and I need help. I followed the Youtube Tornado Twins tutorial and made the worm(only mine is a bit bigger) and use all the scripts to move it and camera control. I decided to make a toon-shaded game from that. I made the worm in Unity and toon-shaded it, but I didn't know how to toon'shade the ground. So, I just made a green plane in Blender and imported it there. But the worm keeps falling through. I've read almost every thread and tried to put everything on (0,0,0), and it's still messed up. My colliders are there on both objects, but it does the same thing! Help!

Thanks

Did you change the Collision Detection on your worm to "Continuous Dynamic"? Planes are tremendously finicky (IMHO) in Unity. If you are moving too fast you'll move right through thin objects. You might consider a box collider instead of the plane collider.

The other thing to try is rotating the plane 180 degrees (upside down). Sometimes it isn't clear which side the normals are on on your imported mesh (disable backface culling or show normals in Blender)... so you end up with your model facing inwards or in the opposite direction. In fact, you might consider making a thin box for your terrain instead of a plane (for testing purposes), just to be sure.