Where Can I Find 'suspended Droplets'?

In the Pigmen's Ravine, there's a mask merchant who sells all sorts of items, in trade for things found in and around the Ravine. I've got all of the masks, except for the Water one- which requires the Suspended Droplets mentioned. Where do you find these? I've been roaming the Ravine for quite a while now, and I haven't been able to find them

 

These are obtainable in Little Wood

 

Even though I'm in the area, I still can't find them. Could you be a bit more specific please?

 

I believe they are dropped by mobs that spawn there, I just know my friend found one there a few weeks ago

 

The mobs here, Fireflies, drop Firefly Wings. They're needed to make a different mask, but they don't drop Suspended Droplets- Unless it's a really rare drop