Approximate
A spoon to measure a geoduck is a very approximate measurement. Geoducks are big, spoons are small. Still, we'll get the approximation going, right?
Do the comparison. A spoonful of geoduck aka a whole geoduck on a spoon. This is a spoonful, right? This is what the recipe wanted, I think...
けい, きょう
ころ, ごろ
None
Maybe this is too much geoduck, even if we're going for an approximate. So, you take the core (ころ) of the geoduck and measure that instead.
That's a little better. Not too much geoduck. Still a lot, but more like an approximate.