My Pink Pet by Mary Louisa Molesworth

"One day I was playing as usual in my own little room, when the door suddenly opened -- " P. 43]

AFTER this I grew fonder than ever of my pink pet. But at the same time I was more careful than before to let no one know of my queer fancy. Emilia's remarks had alarmed me, for I had had no idea that she had noticed my treasure. I could not bear being laughed at, and I intensely dreaded my brothers getting hold of the story and playing me some trick which might deprive me of my favourite. I never played with my shells except when I was quite alone, and deeply regretted there being no key to the lock of my room, by which I might have secured myself against intruders. But as I had always been in the habit of playing a great deal by myself, and had always, too, been quiet and reserved, no one took any special notice of me or my occupations, particularly as every one in the house was just then much occupied with preparations for the approaching marriage of my second sister, Margaret. So I spent hours and hours by myself -- or rather not by myself, for I had for my companions far more wonderful beings than were ever dreamt of anywhere save in a child's brain, and with my pink pet went through more marvellous adventures by far than Munchausen himself.