Barnea candida has a white shell with a yellowish or light brown periostracum, and has pronounced sculpturing anteriorly composed of concentric ridges crossed by ribs with spines. The shell is fragile, narrowly elongate and oval, up to 6.5 cm in length. Barnea candida have large foot muscles and visceral mass, and are unable to retract completely within their shells. The anterior and posterior margins are rounded. The hinge line has a slender projection (apophysis) just below the beak of each valve which serves as the attachment area for the large foot muscles. The umbones are positioned in the anterior third of the shell with an accessory plate, the protoplax, placed dorsally in front of them. The margin is crenulate with spines about the posterior pedal gape, smooth elsewhere. The siphons of Barnea candida are of equal length and united. These can reach 4 to 5 times the length of the shell. The inhalent siphon has 10 to 12 large, and several small, hairs surrounding its opening whilst the exhalent siphon has none. Both siphons are pale brown in colour and minutely papillose, and are tipped with a narrow band of red brown.