Dust Bunnies!!!!!!!
The dirt under grass can be called soil.
Small insects, dust, dirt, or debris could be hiding under the door threshold.
Light coming in under the door is called "light spill" or "door light leakage." This occurs when there is a gap between the door and the floor, allowing light to pass through.
this is called the door sill seal or door sill rubber
door sill.
it is a door sweep
The base of a door is commonly referred to as the "door sill" or "threshold." It is the bottom part of the door frame that sits on the floor and serves to seal the bottom of the door, helping to prevent drafts, moisture, and dirt from entering. In some cases, it may also be called a "door bottom" if referring specifically to the bottom edge of the door itself.
dirt
Part if the door handle pops off. Look under the dirt Handel and you should see it. Then use the key from the remote.
rock guard
lunar dirt
lava?