Suspicious package

I'm looking for a bedtime story to read, and on the bookshelf I discover a small green container, sealed and strapped together with sticky tape. I have an instant 'ugh!' reaction to it, because it smells strongly like wee.

This is the second suspicious package I've discovered in the last week. The first discovery was of two sealed plastic containers sitting side by side at the end of the bath. One contained something that looked like diluted wee; the second contained bath water. Suspiciously, I sniffed, went 'yeurgh', and poured the strange contents down the plughole. But tonight, I am driven to articulate my suspicions.

'Has anyone been weeing into green containers?' I say innocently, while Shark, Squirrel and Tiger are busy watching UK TV History. 'I have!' shouts Squirrel brightly, without a hint that this might be an unusual thing to do.

'Why is that?' I ask, sweetly. Inside I am suddenly panicked. My daughter has gone mad. She wees into containers, seals them, then plants them about the house. How many more am I to find? And where will they be hidden? Squirrel must be traumatised after appearing on stage. She must need psychotherapy to deal with Grit and Dig for parents. But I try to make my voice sound normal, like I might be inquiring about what book she wants to be read for a bedtime story.

'It's for a science experiment' says Squirrel.
'That's interesting' I say. 'What's the experiment?'
'I don't know' says Squirrel, a little impatiently, like I might be mad for asking. 'When we do a science experiment and we need wee, I will have some.'
'Well', I say, 'Do you think that when we need wee for a science experiment we could just wee into the containers then? Wee doesn't keep very well in containers. And the sellotape's not wee-proof. Your green container's leaked on the bookshelf.'
'I didn't put it there!' says Squirrel, indignant. 'I put it on the table.'

Shark and Tiger don't say a word, staring at the underwater scenes on the TV. Clearly, having wee dripping from the bookshelf is quite within the range of normality round here.

'Was that wee in the bathroom the other day?' I go on.
'Yes!' exclaims Squirrel.
Then Tiger looks up for the first time. 'I put that in the bath' she shouts in dismay. 'I thought it was perfume'.