A volzonen slug

The ship landed with a great crash, throwing up a great column of dirt as it did. The slug, using neurolinked control, powered off all systems as it sank into the dirt. The escape hatch opened with a hiss.

As you slithered out of the ship, you could hear it crumple and collapse into itself, leaving behind a small marble that would borrow into the ground for the time being. That was desirable all things considered, when you precured a host and shelter, you'd come back for it. Now came the more challenging situation, acquiring a host. Your ideal one would be something human, preferably one in its adult stages so you'd have a developed body to use, but you weren't turned of by latching and hiding as an animal or child for the time being.

As luck would have it, soon you heard footsteps approaching your location. There was a potential host in the area, and if what your initial scans on landing in this area was right, it would be alone. You positioned yourself in the dirt as you heard it moving. All it needed to do was get right near you and that would be it.