Question: How small can something be and still be considered a "tiny object"?
Background: I have a player who is very excited about using Animate Objects soon, and was trying to come up with options for having a group of Tiny objects available. Obviously this can include bottles or locks, per the "Statistics for Objects" section of the rules (DMG, page 247), and similarly-sized objects. It would probably include marbles, because those are smaller than bottles, and still big enough to hurt. How about a lone 2-inch blade of cut grass, or a 1-inch strand of hair, or a single grain of sand? Each of those is a "discrete, inanimate item" (DMG, pg. 246), but they're considerably smaller than the "Tiny" examples.
I know the GM can rule anything at any time, but is there a referenced "minimum" to being Tiny, either in a firm manner, or strongly implied? Even though they're small, a 1" strand of hair would be magically-empowered by the spell, so I'm not worried about justifying damage. I just want to know if I've missed anything.