Offline copy: How tonsil stones form
The arrow shows a tonsil stone emerging from the front of the left tonsil. It's arising in a gap that has formed between the front of the tonsil and the anterior facial pillar. Salivary debris traps here and becomes a solid entity, otherwise known as a tonsil stone.
To get rid of this, the tonsil needs to be shrunk right back so instead of a narrow gap where debris can accumulate, it's a wide crater where nothing can trap