Back when PBS ran Michael Wood's In Search of the Trojan War series, I learned that gerbils were the bane of archeologists. Everything we thought we knew about the underground layers of different cities of Troy from different eras was called into question. As a result of gerbil tunneling, one could not assume a simple relationship between depth and distance in time.
Now there is a new villain on the scene, this time undermining (so to speak) the world of fossil hunters. It turns out that Osedax has a voracious appetite for bones; and, according to Michael Franco's CNET article, they have probably been around for about 100 million years. As a result, much of the fossil record through which we can track the rise and fall of different life forms is far less abundant than we had hoped because it has been eaten! I realize that there may not many readers willing to shed a tear for evolutionary biologists whose efforts have been frustrated by this little red worm that has neither mouth nor stomach, but the course of true knowledge never did run smooth!