Stages of Development - Concept Work

So I have been trying to find a style of art that I think works for me, and after much dithering I think I might have found a style I like. Although I had already done some pen concepts, I wanted to do some also including a graphics tablet.

This concept is not finished at all, but the start of a concept to do with the inisde of a cavern which the Slime Mould is within.