You don't miss a trick, do you?

Yes, that's an egg. An Aztec egg, made from the same knitting yarn.
He asked about the Aztec's 'larval' form. You and I know that fish don't larvalize; I guess he's an ignoramous ( grin ).

But that's not the Rockworm (caddis larva) I'll tie for the Swap. (Remember the flies I rushed up because you lost my real submission...)