Unstable blocks appear as golden coloured blocks with many brown cracks in them. When crumbling, the block cracks into many small pieces and falls down, fading away.
Unstable blocks are blocks which fall apart when the red feather tribesman steps on them. They will not be regenerated unless the player resets the level. Therefore, the player must be careful when the red feather tribesman is around these blocks, as their destruction may lead to the tribesman's death. This may happen if the tribesman falls in a place where the block was supposed to be, but it had crumbled before.