Howling:Metal Plate

You forgot an important element in the story : Kill the Moon (episode 7 of season 8). It's a metal plate with symbol that prevents the three to be sucked. (in the 29th minute)

This plate is important because it is found on the ship in episode 2 of season 7: Dinosaurs were Spaceship in the 27th minute, as we have seen. As episode 7 of season 7: The Rings of Akhaten when clara lies with merry in the 12th minute and in episode 10 of season 7, Journey to the Centre of the TARDIS, the metal plate on clara in the 7th minute.

In episode 2 of season 8 from the 31st minute, we see several metallic plates with the same symbol.

There may be others but I do not have to find.

(Sorry for my English)