The SCI‐FI‐I‐SPY Catalogue of All Known Types of Alien
#16: HYDROIDS

Identification: gas‐giant blimps full of something lighter‐than‐hydrogen

Variants: methane‐medusas, hydro‐hydras, and ethanol‐anemones

Also Known As: Floaters, Zeppelids, or Hfuhruhurrians

Origin: Jupiter, or equivalent (very occasionally spotted in the solar corona)

LOOKS: bouncy castles made entirely out of slime and nematocysts D
BRAINS: deep, but grotesquely sluggish 75
LETHALITY: cataclysmically deadly, but insular – if you don't go and bother them then nine times out of ten they won't exterminate your species 0.4
CULTURE: a vast back catalogue of slow‐moving, inaccessible arthouse stuff – and it's poorly subtitled, too 99
HARDNESS: an opportunity for some footnotes on gas‐giant physics
TOKENISM: non‐oxygen‐breather tokenism 72

Diet: hydrazine cuisine

Religion: pastafarian

Affiliated With: honorary conveners of the Conciliary Ententicles

Not Affiliated With: the Union of Field Observers, since it would involve too much travel

Not To Be Confused With: the space‐jellyfish variant of Gigabacilloids

See Also: the Necropolypoids, the only oxygen‐breathers they'll take seriously