An unnatural creature (closed RP: Grant and Silvey, possibly Billy Brennan)
She's never seen this tank before.
Working for the Care of Magical Creatures professor, you get used to seeing odd tanks around. Tanks, and cages, and pet carriers, and mini-containment units with manufacturer-guaranteed safeguarding spells that only cover creatures of wizarding-world origin. (No proof against tribbles.) So the new tank doesn't perturb Chance at first and she goes about her business, which today is picking up a bunch of requisition forms for tribble chow and Furby grooming tools. She doesn't give the terrarium more than a cursory glance (oh, that's new, and it's not a terrarium after all, an aquarium, looks like there's water in the tank, but whatever he's keeping in there must be hiding under a rock, or microscopic in size ...)
And then she hears the skittering.
Chitin against glass, many legs.
let us be clear on one fact: Chance is not afraid of bugs, not averse to handling creepy-crawlies. It's not some childish phobia that prompts her reaction, and indeed she tries to reassure herself he's probably just got a really big spider in there. It's a fear that rises from some awareness in herself she can't name or reason away. She has a red marker in one hand, Muggle-made, and the forms drop from her other hand but she clenches the marker as though it were a weapon, as though she could fend off whatever-it-is with this marker
(and she knows, she knows what it is)
because she doesn't know what it is and she doesn't remember where she knows that sound from but she's sure it isn't a good sound. She doesn't remember ever knowing that sound or the slimy cold of the waterworks tunnel where she saw the thing because she never went into the tunnel and she never saw that thing. That improbably alive thing. Extinct for how many millions of years.
She can see what is in the tank now because it's not hiding any more. No, it was never hiding, it was dormant. Sleeping until she came to wake it. It's scrabbling at the glass with its many legs and she remembers the word, its name.
Dicranurus.
Then her mind is full of things she shouldn't remember, and the next little while is a confused babble in her brain. Images. Her grandmother's journal. The red circles around the trilobite specimen in the book, Dicranurus monstrosus, same ugly thing as in this tank, same wicked weird horns. None of it comprehensible. These fragments have I shored against my ruins.
She does not know how much time has passed while she stares stock-still and captivated by the thing in the tank. She only surfaces from it when there's a sound at the door, key turning, and she's got the marker in her hand and she's standing on Grant's desk so she can reach the ceiling.
She realizes, as the door opens, that she hasn't just been standing and staring at the tank after all.