This sort of reminds me of the book "Vehicles: Experiments in Synthetic Psychology" by Valentino Braitenberg. In this book the author starts a series of thought experiments by constructing small "vehicles" which drive around on a table top. The vehicles start with very simple behaviors, then he applies evolution (by vehicles falling off, or being selectively removed) while adding more complex behaviors until the vehicles eventually become intelligent.

In a way the slim mold is a analogous to one of the simple vehicles that ends up becoming more intelligent through the simple mechanisms and evolution.

Book link: https://mitpress.mit.edu/books/vehicles