I can Guess what will happen if they are even allowed to land calmly
and step out.
They could be the Nicest aliens in all the Universes ,
And one. or worse, 100 step out.
And this is how they say Hi where they are from
no one will stop firing till the only thing left will need to be sponged up.
or it will need to be be Bullet Proof.
or it will be the Most Evil & Dangerous in all the universes & Step out looking like this. & this is it's way of showing Extreme Hate just before it opens it's mouth & Gasses everyone. or goes off like a thermonuclear Bomb.