I placed mushroom blocks down and placed others contacting them to creat the pores texture for a build and waited something like 5-10 mins while building other things nearby to give them time to change (because I'd earlier tried doing it quickly and it didn't work. The texture never changed on any of the blocks

Steps to reproduce:

Place mushroom block (I was using brown), 

Place more mushroom to boarder it, break after any account of time

The blocks will stay the same