Karma Nanglu

And that's not just other animals, but it's like, could it be a feature of the animal's own gut?

Could it be something about their gills?

So we kept on looking at photos of these kinds of structures.

Couldn't see any of them.

And then eventually I wound up with these parasitic modern worms that build tubes that are very, very similar.

Yeah, no, totally.

Well, you know, the first thing to remember is for an animal to enter the fossil record is super rare.

Most things are never going to enter the fossil record at all.

And then to have the association is doubly rare.

And then what's cool about this, the shape of this trace specifically, is it's highly characteristic.

And when we look at their modern day relatives, the spionids who produce these kinds of traces, we actually know quite a lot about their behavior and how they produce the trace because spionids on modern day oysters and mussels and other kinds of commercially important bivalves, you know, for eating, have been really well characterized.

And so we kind of know what must have happened.

The larva must have landed on one of these shells.

It bore in sort of

dissolved away a little bit of the shell, built itself a little home, and then gradually elaborated this long tube out of which the adult worm would have stuck its face and its tentacles to feed on water.

Yeah, you know, 480 million years ago, this group of worms was living inside of basically small clamshells, completely content as can be.

Over the course of basically every major mass extinction, this group has continued to be successful to the point that we still are studying this modern group of organisms.

So it tells you something about parasitic lifestyles, how resilient they can be.

Totally, yeah.

Everyone likes to talk about dinosaurs, but, you know, these worms are, you know, a little bit innocuous, but they're still doing their thing.