Primal roaches are similar in basic appearance to normal roaches, though they have different colors, have a slightly more bulbous carapace, and possess larger claws. They also have more health than normal roaches in the campaign.
Many zerg ground units may burrow, become invisible and may be revealed primarily by detectors, and may not move or attack. Exceptions are the roach, which may move while burrowed, the infestor, which may move and cast Infested Terran, and the baneling, which can detonate while burrowed.
Some units can unburrow via autocast, causing them to emerge and attack when an enemy moves into range.