Alien aliens (from alien places)

Some of the most memorable aliens in SF (speaking only of my memory, of course -- your mileage may vary) come from non-Earthlike planets. Maybe that's because the less Earthlike the alien homeworld, the harder it is to make its denizens people in rubber suits. Fictional humanoid aliens are so commonplace they tend to blur together.

So what books, settings, and aliens am I remembering? To name a few:

Mission of Gravity, by Hal Clement (Harry Stubbs). The very-fast-spinning -- and hence, far from spherical -- planet Mesklin has surface gravity varying from a few gees at the equator to hundreds of gees at the poles. The centipede-like natives are the stars -- practically the only characters -- of the novel.

A Deepness in the Sky, by Vernor Vinge. The "on-off" star of this solar system leads to a world plunged regularly into cryogenic temperatures. Its atmosphere freezes out on a regular basis. The natives look a bit like spiders and hibernate like -- well, there's no close terrestrial parallel.

Titan, by John Varley. The main alien IS a terrestrial (sort-of) world.

I'm NOT saying that the only good SFnal aliens are nonhumanoid aliens. That said, I can't help but be struck by how much more vivid nonhumanoid aliens are in my memory.

Have I tried to do aliens who can't even live around humans? I'm glad you asked. Among my contributions to Fleet of Worlds (a collaboration with Larry Niven) is the Gw'oth. The Gw'oth play a small but pivotal role in Fleet of Worlds and move to center stage in our forthcoming Destroyer of Worlds.

Gw'oth (that's the plural; one is a Gw'o) live around deep-sea vents, beneath the ice of a moon like Europa. A Gw'o looks a bit like a starfish crossed with an octopus. Its limbs are hollow (aka, "tubacles"), because the Gw'oth descend from colonies of carnivorous sea worms. A legacy of their colony-form origins plays a big role in ... well, every story in which they appear. (Less crypticism would be a spoiler.)

That's the larger point of this post: Exotic settings beget alien creatures beget novel circumstances encourage memorability. Fiction attains memorability by many paths, of course ... but for this post, I'm content to celebrate a particular path.