Sakana AI's Smart Bricks Recognize Their Own Shape Without Any Central Brain

What if a pile of LEGO-like bricks could figure out what shape they form, detect which pieces are missing, and guide their own repair , all without any brick ever being told where it sits? That is precisely what Sakana AI's latest research, published in Nature Communications, demonstrates. The work, a collaboration between IT University of Copenhagen, Sakana AI, and Autodesk, is the first physical realization of large-scale, bio-inspired 3D self-recognition in modular hardware.

The problem with smart modular systems

Modular robotics has been a research goal for nearly three decades. The dream: snap-together units that can autonomously reconfigure into different structures. The reality has been messier. Most existing systems fall short in generalizing to new shapes or detecting damage in a robust, distributed manner , they often rely on centralized computation, manually designed behaviors, or extensive communication protocols that do not scale well. The missing ingredient, the paper argues, is shape inference: a structure that cannot tell what shape it is cannot meaningfully repair or reconfigure itself.

Previous bio-inspired attempts at solving this stayed either in simulation or in small 2D hardware setups. Existing efforts inspired by biological principles have so far remained either in simulation or in small 2D hardware implementations, limiting their applicability to real-world systems with hundreds or even thousands of components.

Biology as a blueprint

The core inspiration is how living tissue self-organizes. Through local communication and self-organization, groups of cells can assess whether they have correctly formed a target shape, such as an organ, and can actively remodel body parts following injury. A salamander can regenerate a damaged tail that transforms into a functional leg, and simple organisms like Hydra and Planaria can fully restore their morphology regardless of which part is lost. The key insight: none of those cells has a global map. They only talk to their neighbors.

The algorithm the team built on is called a Neural Cellular Automaton (NCA) , think of it as a cellular automaton (a grid of cells that update based on neighbor states) where the update rules are not hand-coded but learned by a neural network. Unlike traditional cellular automata that operate with discrete cell states and hand-crafted rules, NCAs use continuous-valued cell states, enabling end-to-end differentiability and compatibility with gradient descent-based learning algorithms. The team extended this framework from 2D simulations to 3D physical hardware for the first time.