Tortula muralis has an acrocarpous growth habit, meaning the sporophyte is terminal on the main shoot apex. Clusters of Tortula muralis leaves have a whitish cast due to the awns on the end of leaves.
The leaf margin and costa are visibly differentiated from the lamina. The costa extends past the blade of the leaf to form a hairpoint or awn. The hairpoint resembles a long white hair at the apex of the leaf.
The leaf lamina is unistratose and marginal cells are differentiated. A whole mount of a leaf may give the illusion that the leaf margins are multistratose; however, the margins are in actuality unistratose and recurved.
The protonemal stage is uniseriate, with transverse or oblique crosswalls depending on the level of maturation. Protonema contain chloroplasts, which is characteristically different from rhizoids.
The peristome teeth are fused at the base and move hygroscopically, aiding with the dispersal of spores.
In common with other mosses, stomata are present at the base of the sporangium in this species.
Along with Grimmia pulvinata, this is one of the most common and abundant acrocarpous mosses found growing on concrete surfaces in urban areas of Southwestern British Columbia.