Soil blocking is a method for molding seed starting mix into blocks, avoiding the need for plastic seed starting trays or other consumables. Some benefits of soil blocking include better aeration of roots for seed starts, as well as avoiding transplant shock when moving to proper pots or the ground.
Watering soil blocks from the bottom is the best way to prevent the blocks from falling apart. Also, do not let them become too dry as they may crumble - spray often to just keep them moist enough to hold together.