moat, mote

Moat or moat means the man-made body of water that surrounds a castle--
Knights had to lower the drawbridge to cross the moat of a castle.
The estate was surrounded by a moat, like a medieval castle.

Mote or mote ( rhymes with moat ) means a small grain or speck--
The smallest mote of dust caught her eye.
"Let me cast out the mote that is in thine eye..."

Now that you know that, you can say--
"Each beam of sunlight on the water in the moat looked like a mote of sparkling dust."

Note--the borrowed French word "mot" ( pronounced "moe" ) means a witty remark--
Ah! That is a bon mot.
"Mot" is also an old-fashioned term  for one note of a bugle--
It took only a mot to rouse the troops to action.
Note # 2--"moot" ( rhymes with boot ) means having no practical or real effect--
The students learned to argue law by participating in a moot court.
"Moot" may describe a point of an argument that can't be won or settled--
We can argue all day. The point is moot.