Though easy to spot, when allowed to plume, It is hard to see, when held in a room.

Answer: smoke

More Difficult Riddles with answers

More Difficult Riddles

Though I have neither legs nor feet, my use is for to go; Although I cannot speak, I tell what others want to know
Though I wander the earth, I am no longer here. I am pale and I chill everyone near. Who am I?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.
Thousands lay up gold within this house, But no man made it. Spears past counting guard this house, But no man wards it.
Thousands of these come together to make a digital image. What is it?
Three little letters, a paradox to some. The worse that it is, the better it becomes.
Through its wounds, water does run. It once held many but now has none. What is it?
Tom volunteered to be the chief organizer for the world's tether ball championships. There were 657 contestants from around the world. The tournament was set up whereby the winner would advance and the loser would be eliminated. Since there was an odd number of participants, the initial pairing leaves one player out. That player gets a bye and automatically advances to the next round. How many matches will Tom have to schedule to determine the tether ball champion?
Try deciphering this code - S T O E E I T A E S S S I N O Y (Hint - count and you will have the answer!)
Turn us on our backs and open up our stomachs you will be the wisest of men though at start a lummox.
Twelve flags stand equidistant along the track at the stadium. The runners start at the first flag. A runner reaches the eighth flag 8 seconds after he starts. If he runs at an even speed, how many seconds does he need altogether to reach the twelfth flag?
Twigs and spheres and poles and plates. Join and bind to reason make.