These garden dibbles, (or dibbers or dibblers,) are used for planting small flower bulbs, up to about 1" diameter.  I have made grooves at 1" increments to measure hole depth.  Made of Osage Orange, the hardest native North American wood, these will last well with use.  The one on the right is my own, and has already planted about 500 bulbs.  I can make more of these quickly