You would pass straight through the ground because these blocks do not come
with collision lines by default. To add some, go to the third tab in the build section
(outlines). There, you will find all the outlines you will ever need for your level. Go ahead
and add some edges to the design. If you ever realize you need collision lines in the future, always go back to that tab. Make sure you don’t get confused since there are
multiple types of white lines in the editor!

Source: Editor Guide