Refracted light forming a spectrum on the duvet

I was sipping tea in bed with Indie lounging near my feet at the foot the bed. The sun was shining and some rays found a gap through the tree's branches and passed through the glass bottle stopper of an old inherited decanter near the window. the light was refracted and where the beams hit objects several spectra formed.

This patterning of the light happens irregularly at certain times of the year when the angle of the sun's rays (decided by its position in the sky) and their direction conjoin with the particular placement of the bottle. 

At one point a small part of the spectrum (ie not all its colours) appeared on Indie's black fur which amused me. these moments don't last long, and with the scudding clouds I knew was unlikely to wait for me to get a camera. So I opened my phone and grabbed picture of one of the spectra on the duvet cover.