Mock-ups of the so-called 'crabots' are featured in lengthy planning documents submitted to the City of Mountain View Council in Silicon Valley and seen by AJ this week.

As revealed last July, the tech firm has commissioned Thomas Heatherwick, BIG and engineers AKTII to design its extended HQ, which will house 20,000 Google staff.

The 'crabots' are described in the documents as a mash-up of flexible crane and robotic machine.

Much of the internal design of Google's new HQ will depend on the success of the robots which will roam under the gigantic canopies of the sprawling site and lift and shift pre-fabricated components, furniture and services.

'We have studied different options to create a lightweight, flexible and "hackable" system for the building of the interior structures,' the paper continues.