Paidia was the one who again brought him back on track. “This is a fantastic collection, but we've heard that you have other great collections of sculptures.”
Mr Hedgehog nodded, delighted with the compliment. “Yes, that is true, young lady. But I wonder what you could have in mind.” He scratched his chin a moment. “I know!” he exclaimed. “It must be the 4D sculptures. Now this one” - he moved to another cabinet - “this one is a Klein bottle. Not really a bottle. Silly name actually.” He picked it up and the four friends, craning to see, observed that in the instant he took it out of its special holder, its otherwise ceaseless transformation stopped dead and it froze, maintaining its last appearance.
“Gather round, children,” instructed the professor. “This is a 4D object. It exists in other dimensions that we can't see, and normally it moves unceasingly between them. But as soon as it's touched, it stops transforming.”
Paidia was still in her role of spokesperson for the group. “It's great. I love it. But I was actually talking about something else.”
“Ah!” exclaimed Mr Hedgehog. “You're talking about the collection of 'other sculptures'. It so happens I just recently