At the exit to the museum we are all waiting behind three women and their weird pets. I can't make out if they are prehistoric crustaceans or mechanised toys. One is like a giant open oyster lying face down on a dinner plate. Like something from Alien. "He looks good enough to eat," I say and gently poke it with my foot. "Oooh, he loves being tickled," its owner coos, " - before you know it he will climb up on your lap!" The thing slithers onto my shoe.