Dungeon of the Mad Mage (D&D 5E)

While in Waterdeep, the party did a little shopping and some research at the library. They discovered that the fungus they are looking for is on level 11. Heading back down, the proceed to level 8, which so far appears to be mostly swamplike. Following the western wall of the level, they find a broken skeletal leg sticking out of the mud. Just then, 3 mossy lumps rise up and start moving towards them.