These are the only 15 known so far, the last discovered in 2015. Explanation here. Picture source. The Guardian’s account. Account including dates and good animations, plus picture below.
Jo Morgan’s excellent blog contains planning info for use in lessons with great PowerPoint that uses a good Don Steward activity and the whole activity uses three of his resources.
The animation of the new-found tile, below, comes from Skunk Bear where there are more animated tilings.