Is it... wait.  I still know what it is. Nevermind.

This doesn't seem like it would be hard to guess.  Then again, I suppose this is just a hard game.

This is good practice for troubleshooting.  Start by narrowing down your options to only a few possible solutions.

Once it is isolated, then you start picking off the more obvious possibilities.

Then go for specifics.

Finally make your semi-educated guesses.

Questions & Answers:
1. Is it alive?  Debatable.  If I had to pick, I'd say "yes".
2. Is it tangible?  Yes.
3. Is it an object?  Yes.
4. Does it breathe?  Pretty sure not.
5. Is it a mineral?  No.
6. Is it larger than the average human?  No.
7. Is it real?  Yes.
8. Is it a plant?  Debatable.  If I had to pick, I'd say "yes".
9. Is it smooth?  Yes.
10. Is it a flower?  Debatable.  If I had to pick, I'd say "no".
11. Is it a fungus?  No.
12. Is it able to "breathe" CO2?  Not that I'm aware.
13. Is it too small for the average human to see?  No.
14. Does it live underwater?  No.
15. Is it a cactus?  No.
16. Is it a ghost plant?  No.
17. (Hint from Yoss) Is it real and commonplace?  Yes.
18. Is it in a symbiotic relationship?  No.
19. Is it a daisy?  No.

Updated answer to question 8, since a simple "yes" was missleading.

Honestly I don't think anyone is going to get this in the last guess so I'm just going to ask is it a Venus fly trap?

Is it an artpiece??

Since the answer has been guessed at 21 times, and no ones gotten it, I'd say the game's over. Perhaps I am wrong.

Fortunately, I saw the answer in Yoss' private note to himself.

1. Is it alive?  Debatable.  If I had to pick, I'd say "yes".
2. Is it tangible?  Yes.
3. Is it an object?  Yes.
4. Does it breathe?  Pretty sure not.
5. Is it a mineral?  No.
6. Is it larger than the average human?  No.
7. Is it real?  Yes.
8. Is it a plant?  Debatable.  If I had to pick, I'd say "yes".
9. Is it smooth?  Yes.
10. Is it a flower?  Debatable.  If I had to pick, I'd say "no".
11. Is it a fungus?  No.
12. Is it able to "breathe" CO2?  Not that I'm aware.
13. Is it too small for the average human to see?  No.
14. Does it live underwater?  No.
15. Is it a cactus?  No.
16. Is it a ghost plant?  No.
17. (Hint from Yoss) Is it real and commonplace?  Yes.
18. Is it in a symbiotic relationship?  No.
19. Is it a daisy?  No.
20. Is it a Venus fly trap? No.
21. Is it an artpiece?? No.

The object in question is...

(drumroll)

...an apple.

Well, all fruits start as a flower and an apple is a fruit.

That answer made me spill my tea...

I've got one if anyone wants to ask questions.

Is it an animal?

Is it bigger than a breadbox?

Is it a colour you'll find in a rainbow?

Should we wait for jioan to answer?

I guess

Wanna do another one while we wait?

Sure, go for it!

It is a thing?

Out of the category person/place/thing, I assume you mean? Yes.

Safe assumption

Is it bigger than a breadbox?

New one?

Okay I have a thing.. go on and guess!

Is it an object?

Is it an object? -- Yes