Animorphs: Yeerk Neighbors

Two creatures from the Yeerk homeworld (which, like most planets in this series, is unnamed). Along with the Vanarx, Gedd, and Yeerks themselves (these three here: [link]), we know 5 of the "no more than a hundred" species of creatures on that planet.

Big Grey - Some large creature with no apparent head. How and what it eats are a complete mystery, though it is capable of making sounds.
Apparently an iconic creature among Yeerks, as it was used on a billboard advertising trips to their homeworld.

Tonguey - A tongue of some underground creature. It can 'taste' the air for prey, and grabs for whatever comes near. What it does to the things it catches isn't said, we only see it grab is the big grey thing, which is too large to drag underground. Perhaps it drains their prey's body fluids, or it doesn't normally go after such a big creature? Or perhaps it's best not to ask questions and just move on?

BOOK: The Andalite Chronicles
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Animorphs and all related characters belong to K.A. Applegate