Wag worms

When intergalactic Wag Worms are born they look just like a cube. Each year they grow another cube in any direction. Find all the shapes that five-year-old Wag Worms can be.
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative

Problem



When intergalactic Wag Worms are born they look just like a cube.

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Wag Worms


Each year they grow another cube in any direction (except on their faces of course). So a Wag Worm in its second year might look like any of these.

Image
Wag Worms


The next year it grows another cube onto its second cube (not its face cube). So one shape a Worm in its third year can be is this:

Image
Wag Worms


Find all the shapes that a Wag Worm in its third year can be.