It happened during lockdown. The Seattle collectors Kim and Jon Shirley were poring over a thousand-piece wooden puzzle on their dinner table when they began to hear “dings” above them. For 15 years an Alexander Calder mobile, with a bell, had hung silently above the table, “but this was really the first time we heard the work ring,” Jon Shirley tells AIR MAIL. “It just had to happen in that right moment.”