I suspect this is ["Victory Unintentional"][1] a classic short story by Isaac Asimov. ([Scan available on archive.org][2]) 3 robots are sent to explore Jupiter and meet the potentially hostile inhabitants. Although they make no threats or overtly hostile acts, they accidentally kill an experimental specimen by irradiating it, and in other ways prove themselves far more robust than the Jovians. (Entering from space in a ship with no atmospheric control was one factor.) In the end the Jovians decide they don't want to get in a fight with these "Earthmen" and agree to a treaty. The strengths/abilities of the robots that so awed the Jovians were (in story order) - Survived a heat weapon - Survived poison gas - Survived a high-voltage electrical attack - [approximately 30 other unspecified attacks per the story] - Do not drown when submerged - Survived an attack by a gigantic marine creature (noted in question) - Hard enough skin that the creature's teeth did not leave a mark - Strong enough to kill the creature with a slap - Strong enough to casually one-arm toss the creature back into the sea - Do not eat - Do not sleep - ZZ One accidentally destroys a car by leaving without opening its door - It then demonstrates how weak the car was by breaking a "3-inch slab of metal-hard plastic" with slight pressure of its hands - View in the entire electromagnetic spectrum - Broadcast electromagnetic radiation to view with - Composed mostly of iridium - Intense heat doesn't affect them - ZZ One sticks its hand in molten metal, and simply shakes off the droplets (also in the question) - Can adjust their vision to see microscopically - Their presence is fatal to weaker forms of life - Their ship doesn't require a force field; it is not sealed (in question) - Don't breath - Can survive in the vaccuum of space - Can survive in "absolute zero" temperatures of space [1]: https://en.m.wikipedia.org/wiki/Victory_Unintentional [2]: https://archive.org/details/Super_Science_Stories_v04n01_1942-08_cape1736/page/n86