Riddles with year 3

So we read this riddle out twice in my class then asked the children what they thought i could be-

I have no colour, not even white,

but sometimes I’m wide and blue.

Sometimes I’m still, sometimes I rush,

and I can fall down on you.

I can change my shape, I often do,

but I’m hard to hold in your hand.

You need me to make your castle stand up

when you’re playing in the sand.

I haven’t much taste, but on a hot day

Your tongue’s hanging out for me.

Then I am cold, but I can be hot

When I’m in your mum’s cup of tea. 

child 1- 'Is it a triangle?'

Teacher- 'No, not quite'

child 2- 'is it a toilet?'

Teacher- 'erm....it could be something in a toilet...'

child 1- 'The poo on the seat!'