This is classified as original remains because this bug was fossilized in Amber, which keeps its original tissue.

 

 This would be considered a casket because it has the original shape and surface of the pterodactyl fossil.

In order from youngest to oldest...

3) because it's an intrusion
1) the top will always be the youngest
6) This was below the youngest which means it it older than the youngest but not the oldest
4) right in the middle
5) the second to last means it's the second oldest
2) the bottom is always the oldest