Blocks are made of polymer compounds or nanomaterials, which can be connected by a tenon-and-mortise structure, just like Lego, but smaller.
Some blocks can be powered by solar or other energy, with functions such as movement, detection, or logic control.
The life composed of blocks can assemble other blocks according to certain rules, and can even use natural resources to make new building blocks.
This is different from a robot, because the processor or nervous system is also made up of blocks.
The level of block is lower than the cell because it does not embed genetic material (but itself can be used to form genetic material), but it is higher than the atom because it has specific functions and physical properties. Roughly equivalent to protein and some other molecules.
The waste and remains of one "species" can become raw materials for other "species".
This system can be regarded as a physically feasible analogy of cellular automata.