By the time you finish digging a coffin hole with nothing but a spoon, you’ll be an old elderly person. Digging with nothing but a spoon takes a long time, especially when the hole needs to be big enough for a coffin. You might as well be digging it for yourself at this rate. By the time you finish, you’ll be all wrinkled and elderly and just about ready to keel over.
Now that you’re elderly (and probably about to die) you suddenly crave some delicious roe (ろう). Salmon roe, sea urchin roe, tofugu roe, doesn’t matter. Your old, tired bones need roe after all that hard work!