After supper today, I noticed Simon's loose tooth was missing. He must have swallowed it. His new tooth is already half way in, so it just pushed the old tooth out. It couldn't have been more effortless and painless.
Here he and Alice are, the next morning, discovering the coin and note from the tooth fairy. The note explained why he was still getting a coin even although he swallowed his tooth. Simon wouldn't have needed any explanation, but Alice remembered getting a note when she swallowed her tooth, so we had to do it for her. Tooth fairies are very consistent.