Platypus decides it's the perfect day to go collecting.

He finds a big rock, an old shoe and a broken umbrella, but none of these are quite what he's looking for.

Then he finds a curly shell - just right! But it keeps going missing from his special box. The 'thief' turns out to be a little hermit crab living inside the shell so Platypus takes it back to the sea where it belongs.

Luckily there are plenty of unoccupied shells for Platypus to collect - and keep!