The Martians' arrival on Earth is aboard a large, cylindrical spacecraft launched from some kind of immense space gun on Mars.
This is mounted on an articulated arm attached to the front of the tall tripod, called a 'fighting-machine' in Wells' novel, which travels across the landscape destroying humans and their habitat.
A secondary weapon, the "black smoke", is a toxic gas released from canisters launched at a distance from bazooka-like tubes, referred to in the novel as a "gun," which kills humans and animals alike; it is rendered harmless by Martian high-pressure steam jets and water.
These secondary Martians are bipedal, nearly 6 ft (1.83 m) tall and have "round, erect heads, and large eyes in flinty sockets"; however, their fragile physical structure, made up of weak skeletons and muscles, would have been broken by Earth's heavier gravitational pull.
It is reported that several Martians attempt to "stand" on their tentacles, implying that they are capable of locomotion in this manner while in Mars' lighter gravity, but not on Earth.
He makes mention of a "queer hooting" sound but attributes it to the exhalation of air before fatally transfusing blood from their human victims.
I was somewhat startled, then, in looking at the head and centre of the great military system of Mars, to find in his appearance a striking confirmation of the speculations of our terrestrial phrenologists.
When Kang's interference of the timestream shatters it, random events of history occur in present-day New York City, including the arrival of Killraven and the Martians, piloting their Tripod walking machines.
[2] In the 1953 film adaptation, the Martians are short, brown creatures having three-fingered hands with suction cups at the end of long arms and a cyclopean eye divided into three sections: one red, one green, and one blue.
Wells' War of the Worlds, also known as "Invasion", the Martians resemble a short, green, disc-like head with four long tentacles acting as legs.
In the sequel War of the Worlds 2: The Next Wave, the antagonists are the "squid-walkers", a cybernetic race of tripods controlled by a single entity inside their mothership.
Their fighting-machines are extremely tall, with very long silver legs and numerous appendages, and emit a similar sound to the "Ulla" Wells described.
The aliens crash to Earth in cylinders, which more closely resemble a meteorite (a similar aspect was used in the 1953 film adaptation), and spread their red weed during the invasion.
It is also made clear that the aliens are not Martians, but originate from a more distant planet flooded with water, which puts the long legs of the Tripods into motion.
Because science has revealed that the red planet is devoid of intelligent life, the concept of using Martians is sometimes dropped from some adaptations as it is no longer deemed realistic.
One of the earliest known to take a new spin on the invaders was in a pilot presentation made by George Pal for an unrealized War of the Worlds TV series.
Though Pal's 1953 film is established as a basis for the look of the invaders and their technology (their war machines bearing no clear dissimilarities), there is no seeming intended continuation.
These invaders, depicted only in production art, only differ in certain detail as they appear leaner and their cyclopean eye sporting apparently only a single color.
Though some minor details are given away to indicate that their home planet was not Mars, it is not confirmed on-screen until midway through the season that they originate from a world named Mor-Tax.
With their beautiful planet becoming uninhabitable from a dying star, they invade Earth with plans to take it over to preserve the traits that it shares with their old world.
They are incredibly intelligent, able to communicate in seconds over light-years of space, create effective booby traps, and even adapt seemingly normal human objects for their own purposes.
However, their intelligence lends itself to their one true weakness: their hubris, as it is established that they often claim victory before it is accomplished, do not admit to their mistakes, and with the exception of the Advocacy, those who fail are executed.
In Sherlock Holmes' War of the Worlds, Professor Challenger theorizes to Sherlock Holmes that the Martians came from another, wetter planet due to their seeming familiarity with the ocean while battling the Thunder Child; their small lungs (which would have been inadequate in Mars' atmosphere); and the fact that no construction was evident on Mars before the 1894 opposition.
Their apparent struggle to move in Earth's gravity is given as a mixture of caution and embellishment in the accounts of Wells, "the known atheist and radical".
In the Scarlet Traces comic, it is eventually revealed that the Martians came from a planet that exploded to form the asteroid belt; they then settled on Mars, driving the native species into extinction before launching similar wars against the races of Mercury, Venus, the Moon, and finally Earth.
In Ian McDonald's short story "The Queen of Night's Aria", a sequel to The War of the Worlds published in the 2013 George R. R. Martin and Gardner Dozois anthology Old Mars, the Wells Martians are named the Uliri.