How did they achieve this effect with painting?

[Willowtails]

First post. Have found a lot of useful info in these forums, but now I came across something that I can't seem to find the answer to.

I found these pictures, and I really like how they painted this, but I can't figure out how they did it. All I know is they did it all by hand, not airbrush. 

Can someone explain to me how to achieve this? 

Thanks in advance. Tom

[MikeRock]

It looks like sponge work.

 

God bless

[chuck123wapati]

it looks like it was sponged on, either paint or dye then the notes, snail were painted. I think you could create the mottled effect with either, with some practice. Beautiful work indeed.

[Willowtails]

I guess I just have to grab a sponge and start trying some stuff out and keep practicing then.  

Thanks for the answers.