Neptune's Harvest Crab Shell Multi-Purpose Plant Food 2-3-0 23% CA 12lbs Neptune's Harvest organic crab shell is an excellent dry organic source of NPK (2-3-0), calcium (23-percent) and magnesium (1.33-percent) It will also help with nematode and fungus problems Crab shell can be applied with our kelp meal (not included) to increase organic matter and retain moisture in the soil