Although many, if not most, members of the family have declined dramatically in recent years, Tampico pearlymussel numbers have held up rather well. While riverine populations have been subjected to dewatering during droughts and severe scouring during floods, some reservoir populations have flourished. Today, reservoirs from the Rio Grande to Abilene and Waco still support significant populations of Tampico pearlymussels, as do some rivers and streams. This unique unionid reaches over 130mm in shell length and has a general shape reminiscent of Mercenaria or Spisula. There is no significant external shell sculpturing.
Coloration varies from yellowish-brown with faint green rays to dark brown and black.
Internally, nacre is typically purple, but may be lavender, pink, orange, salmon, white or multicolored. Boldly-colored nacres are comparable to anything grown on a tropical coral reef. Although some individuals have taken pearls over 10mm in diameter and valued at thousands of dollars, true gem-quality pearls are very rare . . Realistically, if pearls were common, their value would be far less. Habitat of Tampico pearlymussel ranges from relatively small streams to large reservoirs.