A delayed coking process in which shot coke and thermally cracked coker products are produced from a sponge coke- and/or transition coke-forming resid feed comprising sponge coke asphaltenes by mixing heteroatom (preferably nitrogen) containing asphaltenes from a shot coke-forming resid with a heated sponge coke-forming resid to form shot coke directing asphaltene aggregates in the resid. The mixture of resid with the added asphaltene is held at an elevated temperature to allow co-aggregates of sponge coke and shot coke asphaltenes to form which, upon delayed coking promote the production of a free-flowing shot coke product.