My slug might be dead, help?

[Dumbledore]

Yesterday I found a garden slug attacking my lettuce. I wanted a pet slug, so I took it inside. I put it inside an empty container with the lettuce leaf I found it on, a lettuce leaf from the fridge, and a grape that was split in half. I also put a little toy tire thingy that I washed really well with my special contacts soap (no residue, figured since it's safe for me to put that stuff in my eye, it's fine for slugs). He crawled around and seemed to enjoy it. After a while he slept in the tire thing. Then he came out and started playing again. I watched a movie with my brother, and when I checked on him, he had retracted his tentacles and looks like a blob. This was yesterday afternoon, and today he still hasn't moved. Is he dead, or is it just sleeping, or what?

[pinkunicorn]

He's likely sleeping. I see that often in slugs (snails, too) after adopting then from the wild. They go a bit nuts first, exploring and enjoying the offered foods and then relax when the novelty wears off. You can gently prod his tail or stroke along his back lightly like you would pet any animal, and see how he reacts. At first they are a bit afraid of being touched but even slugs will get used to being handled and even enjoy it!

Don't wash your hands with water after touching a slug, btw. First wipe the slime off on a paper towel etc dry material, THEN wash hands normally! Slug slime, especially that of Arionids, the often brown/maroon/black coloured guys with a cute, smallish black head (yours might be one of these as they are common - I love them sluggies!), is thicker than that of snails to keep them extra protected from drying out and it absorbs water for the same anti-drying reason... so any slug slime on your hands will just get slimier and thicker when it comes into contact with water!

[Dumbledore]

He's not reacting, and there's a kind of weird smell. Does that mean he's dead or do all slugs smell bad? I found another one today, and he looks the same- brownish but tan head. And that explains why it took so long to wash, thanks!

[pinkunicorn]

Not reacting at all? Do you see his skin kind of ripple?

Smell sounds bad. Is it coming from the slug? That would mean he is dead. But they don't stay attached to a wall if dead. It seems very odd that he would just... die within a day!

[Dumbledore]

No, he wasn't reacting at all, and it was coming from him, so I buried him. D': But I found another slug yesterday morning, and he's fine and happy, just crawling around his tank and pooping and eating, so I really don't know what happened. Maybe could you check your thread about snail babies today?
Edit: He wasn't attached to a wall, he was on the floor.

[muddydragon]

What's in your contact lens cleaning solution? is it likely to be a mild saline solution which may have upset the slug?

[Dumbledore]

It wasn't the solution that I put my lenses in overnight, it was like a special soap that I'm supposed to wash my hands with before to get rid of anything on my hands that wouldn't be good to get in my eye. And no smell, no residue.

Edit:

For new slug, no tire and no grape, just lettuce and dirt from outside where I found him, and he's doing great. He even pooped on my hand when I was holding him... not a perk of snail owning. 

[Dumbledore]

I now have 4 slugs, and they are picky! All they eat is watermelon and lettuce. I offered strawberries and banana, and they wouldn't eat it, but they hopped right on the watermelon. Any suggestions to make sure I don't have to start growing watermelons?