These were old when life was young and bear no sign of age. Each seems quite new and freshly made. You imagine polishing hands wringing each gleam from the liquid shard-like spikes, then wandering off, just as you arrive, to leave it shining whitely in the butter-yellow light.
The shapes a jewellers drunken rave, a Fabergé masturbatory fantasy. Endlessly symmetrical disco-ball-bright pinpoints. A prism'd interior. The lantern light refracts and paints wierd spectra on the sallow rock.
Not all the Radialaria were fossilised in precambrian ooze, or leant their genes to species yet to be. Some survived, exceeding their design. An unpredicted maladaption cracked their genes and killed them as a breed. But kept them as one thing. The humming engine of evolution, unchained from sex, went mad inside the cell.
These are not the children of the creatures of old. They are the very thing. The same anonymous cell that floated in the worlds first sea, but still alive, and vast.
The liquid crystal has a hippo's mass, but packed with mind. It needs the size to store its plans. Neither predator or prey, the Radiolarian has two to three million years of survival oriented molecular memory held in recombinant chains. It cannot think. They have no brain as you would understand, but acts, reacts, adapts, recalls. The surviving Mega-larians have faced almost every threat that life can face, and many lost to time. They know it all.
Sometimes they need to eat.
They move like leaves, dancing down a street in wind. Corrugated edges kissing at the ground. Or spooky children racing in a twilight park. They're light, or seem so till they hit, pinning you bloody on the rock. The liquid spikes like supple knives curl round. They drink your blood. You watch the red mist briefly in the gem. Then gone, like match-smoke patterns in an opened room. They need your GATTICA spirals to wipe clean, and re-record with threats they've yet to face.
Careful observation of a Radiolarian before or during combat, can give you clues to the kind of threats present in the local volume. A beast begrimed with ice might have fought the Ignimbrite Mites, a creature wild with multicoloured light may have duelled the Eigengrau.
Radiolaria will adapt to any blow, spell or tactic, no matter what it is, the moment after it is used, or, if the players are being boring, the moment before. Interesting players may survive. Dull ones never will. Plans don't count. The Radiolarian already has all the plans. Innovation counts.
I have a problem with this thing. It's already a blind, climbing, cave dwelling spider with awful hooks that point each limb. And it's real name is actually Trogloraptor, which is better than anything I was going to come up with. I was going with 'Hook Spider'.
There's almost nothing I can add to make this more charismatic or unnerving than it already is.
Perhaps it carries children on its back as eggs. Like anyone's children. Yours maybe. Attacks like a hook horror with eight legs. Intelligent. Translucent ochre. Needs more kids to put its eggs inside. And the kids are still alive and crying for help. Because that's it's hunting tactic. It eats the parents when they come looking.
Obviously I'm making it giant, and self-aware. Though I'm tempted not to as the child-egg-bait thing almost seems more horrible as a fucked up hyper-specific evolutionary tactic. So maybe as smart as an Orca or a wolfpack.
The sound of weeping children in the darkness is a classic. Because you know there are kids to be rescued. And you know the only reason you can hear them is because Trogloraptor is hunting you and it wants to draw you in. I'm imagining one long slender limb curving up over its own back to gag a weeping child that's bound in silk. It stares down from the wall, watching the lanternlight pool, waiting for you to approach.