Swamped

You can both see and sense something moving beneath the water. But you can't see much of it from here, and you're only detecting a small trace of ether. Not enough for any spell you know of.

But what you can see has a metallic color to it. Perhaps it's ether-resistant metal and what you're sensing is the remnants of a spell that it blocked?

Except, you don't know of any metal that can hold up well against both ether and salt water. So even if that were it, you're just left with another mystery. As if you didn't already have enough of those.

You point it out to Resk and ask what he thinks. He just shrugs.

"Doesn't really look like anything to me. Can you get a better look with a spell?"

"Technically, but it's harder than you might think. For reasons I imagine you don't want me getting into."

"Probably not," Resk grumbles. "And it's just a curiosity right now. Might be important, might just be a discolored shark. And I know you don't like to cast spells frivolously. So I guess the question is, do we have any way of figuring out if it's important enough to go to that trouble?"