It strikes me that an acidic lava slug with the ability to tunnel through just about any mineral might not be the ideal thing to bring aboard a space ship.

I mean, it manages to not be the most bizarre thing on my ship, but it's the only one I'm pretty sure will kill us all.

they make great foot warmers (keep feet at a distance unless they belong to person you are interrogating ...).

might also make great tribble toasters....

They are the Ideal pet to keep around for when you're trapped and there's no way out.

"sizzle sizzle"
"What's that Hortie? has little Timmy fallen down a deep hole in the ground again?"
"sizzle sizzle"
"Great! that kid is annoying, can you dig a few more, there's a couple of crew members that are getting on my nerves."
"Sizzle sizzle"

And now...BRING ON THE EXOCOMPS!!!!!!!!!!!!!!!!!!!!!!!!!!.

I bet Sulu would have given his right arm to have had one on his Away Team during the "Enemy Within" episode.
(..or even a Shuttle Pet, for that matter... LOL)