Had a mad marketplace splurge back in July and ended up with this half-moon-shaped tinyquarium for five yes 5 quids! Now that it's been super-quarantined I wish to delight and distract Mrs R by making it come alive.
It came with pump, filter, light, classy gravel and decor bits as pictured below. No heater. Not attached to any idea yet. Rules are anything that is practically possible/would be happy in there! Too small for fish by the look of it. It really is small about 8 litres I’d guess:

Ideas so far:
Aquascape/terrarium? plants/mosses/bark?
Insect? ie silverfish world (we have some already!)
Semi-aquatic setup/paludarium with small pond insects/shrimp, etc?
Something as garish as that needs sea monkeys and a bobbing plastic diver.
🤣 I should have taken a ‘blank slate’ pic, because the tat has to go. And ...pics are good!

Woodlouse kingdom
*PHOTOSHOPISTS ASSEMBLE!*
Hmm... I like woodlice. But...(democratic interval), she says ‘no woodlice, cockroaches or slugs, brrrrrr. Centipedes neither’
I did a reverse image search and found this!

Spectral seamonkeys? Ohhhhh

Was it on the forum someone posted a video of a sealed ecosystem in a bottle video? Think it had been kept going for 14 years or something. Had a plant inside which some little critters ate. If there were too many of them the plant couldn't feed them and they'd die out, then the plant would flourish then they'd flourish. Etc. It lead me to another of the same type, but seawater based. Had a starfish and crab accidentally caught when the person was collecting material for their ecosystem off the beach. They grew from tiny and died within a month or two. Could go for that perhaps?
They grew from tiny and died within a month or two. Could go for that perhaps?
Looking for something more long-term (optimism!) Although it could evolve. I like the evolution/life-cycle thing. Over the weekend I’m going to take the tank back to bare bones and clean it. Then put suggestions to the vote on Sunday night. 👍🏼🍺
Neons and tetras?
I am sure there's an episode of South park about Sea People that you could refer to.
Bong.
Does it have a lid? If you go for fish without a lid you will lose a lot of water due to evaporation, and also possibly fish since they can actually jump...You'll also get a grimy layer of dust floating on top of the water without a lid...
Otherwise, I'd say cats...It's been demonstrated that they are liquids so would be happy in something like that

A gladiatorial arena for some form of fighty insect. You could have a tiny colosseum with Lego men (or silverfish held down with Velcro) as spectators. Possibly some sort of LCD scoreboard next to it.
Surely it has to be stick insects..... or a really tiny Boa Constrictor.
There’s nae lid, cap’n
Crisps
Car keys🤩🤩
I presented it to her. Smile achieved!
Being completely honest, I feel in some small way that to have underachieved. As a ‘unit’ it lacks a certain something. It has an unfortunately tawdry allegorical air about it. I don’t feel I can quite relate to it. Except for the crisps part.

Good choice although I’d have gone for two flavours.
^ Thanks. In defence there was room for one only. That’s a mirror on the back! More symbolism and allegory!
I name it:
‘Tankenstein, or The Modern Pringkeytheus‘
Herb garden.
Or just a load of Cress.
Some teeny tiny orchids - as a shopping list try trisetella,restrepia antenifera, neofinetia falcata, lepanthopsis astrophera, some sort of pleurothalis or stelis - all happy with bright indirect light and normal room temperature, just keep them misted.
Or Pringles and car keys.
Apologies for hijack.... Those wee orchids the purist mentions... How would one go about buying those? From legit not ripped out of the forest kinda suppliers?
There are (were) a number of orchid shows during the year where specialist growers would come over with a bunch of stock. The RHS used to do a big show in spring (in London) but it's gradually been diluted and faffed with so I've not bothered for a few years, and also the Orchid Soc of GB have shows and events, and some members specialise in the miniature orchids.
A couple of bought from are https://www.kopf-orchideen.de/en/ and https://www.ecuagenera.com/ but they were at shows so no shipping costs - there are quite a few legit growers in Germany and the Netherlands.
Something as garish as that needs sea monkeys
Man Behind the marketing of Sea Monkeys (Harold Braunhut) has an "interesting" story...
https://www.splcenter.org/fighting-hate/intelligence-report/2004/hitler-and-sea-monkeys

Ants. For real.
You've missed flying-ant-day for collecting a local variety this year but you can get them by post.
My lad has a small terrarium with a European harvester ant colony that is building up from a queen + 10 workers, from one of the online ant shops. They do interesting stuff like dig chambers and store seeds and whatnot. We collected a few black garden ant queens which are also doing well in their test tube nuptial chambers, they'll need a bigger nest around spring time next year.
Needs a "secure lid" ...!
Youtube is full of ant keepers.