On My Own Wiki

The big rock can be useful in many ways.

If you tap it or move it on any given day besides the first day of spring (100%) and any day of winter (0%) you will have a 50% chance of finding an earth worm underneath them on any given day.

If you gather rocks in your inventory, you can set them up outside of the cabin to farm worms so that fishing becomes a more sustainable way of living.

You can craft two rocks and make a stone axe head which is non-deconstructable and can be used to make a new axe using a rope and a stick. The stone axe gives no advantage or disadvantage compared to the axe and would be a waste of rocks and rope if made for no reason.

The rock is used to make an arrowhead by crafting obsidian with a rock and the rock is not consumed during the crafting so using one rock can make an unlimited number of arrowheads as long as you have limitless obsidian.