How to fit a round bottle into a square hole?

It's not that clear from the picture but actually the stuff in the bottle, pine oil soap or mäntysuopa as it's called in my native language, has soaked the soft plastic and shaped it into a square.

Mäntysuopa is an old cleaning liquid from the days when there were no chemically engineered alternatives available to blow the dirt away. Being a product of nature, it's far less dangerous and, to my big surprise, powerful than its' more modern alternatives.

Nature 1 - manufactured plastic objects 0.