Like many other snails, mystery snails (Pomacea bridgesii) have shells that protect their soft bodies from injury and predators. While the snails do not “live in their shells” as most people believe,[1] they often recede into the shells for protection and defence against predators and harsh environmental conditions.


Mystery snails do not shed their shells because they are a permanent part of their bodies. The shell is created and connected to the snail’s body by a specialized layer of tissue called the mantle. Therefore, as the snail grows, the shell also grows to accommodate it.

The mantle secretes calcium carbonate and proteins that make the main composition of the shell, making it a hard, protective structure. We recommend providing mystery snails with enough calcium to ensure a healthy shell.

A peeled or broken mystery snail shell

Snails do not shed their shells at any stage of growth and development since these shells are part of the snail’s exoskeleton. However, cases of dropped, broken, and peeling shells are not uncommon.

Why is my mystery snail’s shell peeling and breaking?

Mystery snails are peaceful creatures and will not attack their tank mates. However, whenever they feel threatened, they retreat into their shell, close the trap door, and only come out when they feel safe again.

If your mystery snail sheds its tail, it will likely die due to exposure to harsh conditions or predator attacks. A healthy snail will have an even and strong-looking shell, while a broken or peeling shell shows the snail is unhealthy.

Here are common reasons for a broken or peeling mystery snail’s shell:

Shell erosion

As we already know, a snail’s shell is composed mainly of calcium carbonate. A low water pH in the tank can dissolve the shell, making it erode away over time.

The exact pH where the shell begins to dissolve is not very clear, but it is believed that if the water has a pH below 7.5, the snail’s shell will erode away and appear to peel, chip, and break.

Best fix

Maintain the ideal aquarium water parameters for mystery snails – a pH of 6.5 to 7.5 and a hardness of 150 to 300 ppm.

Here is how you can increase and maintain the pH level in the tank.

  • Changing the water regularly
  • Adding substrate such as crushed coral
  • Increasing oxygen concentration in the water. Low oxygen concentration is known to lower the pH.
  • Adding baking soda
  • Adding eggshells to the aquarium

Calcium deficiency

A snail’s shell is a hard covering of about 95% calcium mineral deposits, which is why mystery snails need plenty of calcium to maintain healthy and strong shells.

Lack of calcium makes the shell weak, peel off, and break. Since the snail has a soft body, it is left exposed to harsh environmental conditions and predators if the shell breaks or peels off significantly.

Best fix

If your snail’s shell is fragile or shows signs of peeling and disintegration, provide calcium supplements to strengthen it. Great sources of calcium for mystery snails are kale, lettuce, spinach, basil, zucchini, and cabbage.

You can also add cuttlebone in the aquarium to provide slow-release calcium into the water from which the snails will obtain their dietary requirement of the mineral. You can also increase calcium content in the water by water mineralization or by adding calcium supplements.

Predatory damage

Snails kept with aggressive tank mates such as betta fish and crayfish may experience damage to their shells from predatory attempts.

According to Carlos E. Cintra-Buenrostro of the University of Texas s Rio Grande Valley, nibbles, chips, and peels are some of the most common types of damage on snail shells from predatory activities.[2]

Best solution

If your snail’s shell shows any of these signs, I recommend you move it into a safer tank where it will not be preyed upon or attacked by other aquarium inhabitants.

Accidental falling

Mystery snail shell breaking
Snails do not shed their shells. However, they can lose them from breakages, erosion, and peeling.

Mystery snails love to climb on the aquarium’s glass and any other surface and will even attempt to climb out of the tank.

Although they do this to explore, it is dangerous because they often fall onto hard surfaces with the impact breaking their shells.

If the need to crawl out of the tank is heightened, you might want to check the water quality. Unbearable tank conditions can cause mystery snails to want to leave the tank, which can cause them to fall on hard surfaces and break their shells.

Best solution

You can prevent accidental falls and shell breakage by covering your tank. You’ll still allow for their normal movement in the water and the surface, except that they won’t get out of the tank.

Exposure to toxins

Exposure to toxins, such as heavy metals or acids, can also interfere with the snail’s ability to form and maintain its shell properly. They can disrupt the pH balance of the surrounding water, making it more acidic or alkaline than normal. This can cause the shell to dissolve or erode over time.

Toxins can also interfere with the snail’s ability to absorb calcium from its diet, resulting in weakened shells that crack easily.

How to fix a broken mystery snail shell

Mystery snail broken shell
A broken mystery snail shell.

Most snails can repair minor damage to their shells. However, if the damage is severe, you can step in, help, and hope it will heal.

Here is how you can help:

Repair the crack

Patching up a crack on a mystery snail will help in the healing process, and also, if the body tissues are injured, it will prevent an infection.

How you mend the crack is essential because it will determine if you have helped or worsened the situation.

Applying glue directly to the crack is NOT recommended because the glue might spill onto its body. You can put a piece of another snail shell, eggshell, or anything else that can cover the crack.

Improve tank conditions

You must intervene immediately if your tank conditions are not ideal and cause the eroding shell. Ensure the pH is between 6.5 and 7.5, the water hardness between 150- 300 ppm, and the temperature at 68 – 82°F.

Additionally, test ammonia, nitrate, and copper levels and ensure they are maintained at zero because they are toxic to mystery snails. Also important is to keep the recommended number of mystery snails per gallon to avoid overcrowding the tank.

Provide calcium supplements

To heal the affected mystery snail, you will have to feed it with enough nutrients. Also, you should check if the mystery snail is ailing due to calcium deficiency. Feed it with calcium-rich food, and you can also use supplements.

What happens if a snail loses its shell?

In most cases, a snail that loses its shell will die soon afterward since it will be left completely exposed to the environment and predators. Environmental stress and injury are the main causes of death in snails with a weak, cracked, or peeled shell.

Therefore, if you see a snail not moving or coming out of its shell, it is probably dead. It does not mean your mystery snail has shed its shell. It probably died and got eaten by a tank mate.


Mystery snails do not shed their shell because it is attached to their body. A mystery snail detached from its shell is likely dead or dying. However, their shells can be damaged by aggressive tank mates, falling, calcium deficiency, or intolerable water conditions.

References and further research

  1. LAUREN DYKMAN, Woods Hole Oceanographic Institution; Following snails around the world

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