The environment was not too good for noticing it and identifying it for what it truly was, so it could have been left behind.
The cores were one item that dropped that was valuable and useful in many ways, but so were things like that, which would be left behind.
The value of such items varied, but they could be bought and sold to be used as materials to make Spirit weapons or tools.
If it dropped from a Spirit or Evil Spirit that was a much higher grade, then the value would be much higher, just as such a dropped item could be used to create a tool or weapon of a higher grade.
The higher the grade of the material, the better the item created from it, as such an item would be a lot more durable and deadly.
If such an item were larger than it was, it could be used to make one or more items, just as it could help to make something bigger than normal.
