I started this design for one of the mushroom zombies. I thought since the zombies are humans who have been infected by fungus that it would make sense to have a human body proportions. I decided to add the vines around the body to reference the idea that the character has been lying underneath the ground for a long time and his almost become one with the ground. This is also why I added the long vines sprouting from the hands.

One of the other members of the group designed a slightly different looking fungal zombie which was much skinner and crooked. I really liked this design so I think I will be looking at that style of design for developing my characters further.