The Evertoothed

~24.5 million years ago, as the Self begins tentatively exploring its surroundings...

One of the searching swarms has returned early with something it found. Not a new wall, which was its goal, but something interesting nonetheless. It came across a pile of sharp objects it thinks might be teeth. They are as pointed as the teeth inside each part, but flat instead of curved, and the edges aren't smooth.
The swarm reports that there was an abundance of these teeth, all the same shape but in varying sizes. The largest are half the size of an individual part, and the smallest a little bigger than the end of one of a part's tails. Our guess is that these belonged to the animal that the Singer called "Evertoothed". From the way they were found in a rough arc, it's more than likely that all these teeth came from a single one.
We're uneasy about this discovery. The Singer told us that the Evertoothed were dangerous, so much so that they, along with the Diggers and Spitters, all agreed to defend each other against them. Did they fail? Is that the reason the Singer hasn't come to speak with us in so long?