REEF GUARDIAN
Chest probabilities
Check the rewards and their chances before spending Pearls. These rules apply to version 1.1.9, build 23, using reward definitions from Studio revision 57.
Special Chest
1 chest: 100 Pearls. 10 chests: 900 Pearls. Each chest makes 6 weapon selections and awards matching weapon fragments for each selection. The first 6 selections use different weapons. This starts again for each chest in a ten-pack. Owning, equipping or upgrading a weapon does not change its chance.
Rewards depend on your highest stage cleared. The eight starter weapons are eligible from the beginning. Other Normal and Rare weapons become eligible after Stage 3, Unique weapons after Stage 6, and Legendary weapons after Stage 10. The table lists every eligible weapon for the progress you select; all others have a 0% chance.
Highest stage cleared: 0. Selection: 1.
The selection column shows the chance before opening, averaged over possible earlier selections in that chest. The last two columns show the chance of receiving that weapon at least once in the whole purchase. A fragment reward counts as receiving that weapon's fragments, not unlocking the weapon itself.
| Weapon | Rarity | Selection 1 chance | At least once in 1 chest | At least once in 10 chests |
|---|---|---|---|---|
| Bubble Blaster | NORMAL | 13.440860% | 75.452866% | 99.999921% |
| Polyp Turret | NORMAL | 13.440860% | 75.452866% | 99.999921% |
| Bone Spikes | RARE | 9.677419% | 72.764783% | 99.999775% |
| Turtle Spin | RARE | 9.677419% | 72.764783% | 99.999775% |
| Octopus Arms | RARE | 9.677419% | 72.764783% | 99.999775% |
| Spark Shrimp | RARE | 9.677419% | 72.764783% | 99.999775% |
| Tidal Ring | RARE | 9.677419% | 72.764783% | 99.999775% |
| Brine Pool | UNIQUE | 24.731183% | 85.270352% | 100.000000% |
How earlier selections change the next chance
A weapon already selected in this chest has a 0% chance for the remaining selections. Choose up to 5 earlier weapons below to see the next selection's chances. Order does not change these chances. Clear this list when starting the next chest.
| Weapon | Next selection chance |
|---|
If a rarity has no remaining eligible weapons, that rarity cannot appear in the next selection. While all four rarities remain available, their next-selection chances are Normal 25%, Rare 45%, Unique 23%, and Legendary 7%. These are shared equally by the remaining weapons of each rarity. When some rarities are unavailable, the relative chances of the remaining rarities stay in the ratio 25:45:23:7.
Fragments per selection
At highest stage cleared 0, each normal selection awards 3, 4 or 5 matching fragments, each with a 1/3 chance.
Quantity is rolled separately from the weapon selection and is the same for every eligible weapon. To find the chance of one weapon with one quantity, multiply that weapon's selection chance by the quantity chance below. This table covers normal selections; the ten-pack guarantee is shown separately.
| Matching fragments | Chance |
|---|---|
| 3 | 33.333333% |
| 4 | 33.333333% |
| 5 | 33.333333% |
Fragment quantities grow with your highest stage cleared. Each of 3, 4 and 5 is equally likely as the starting quantity. It is multiplied by (1 + highest stage cleared / 18)² through Stage 10. Above Stage 10, the multiplier is (1 + 10 / 18)² × (1 + (highest stage cleared − 10) / 40). If the resulting number has a decimal part, it rounds up with that decimal part as the chance and rounds down otherwise. For example, 7.2 becomes 8 with a 20% chance and 7 with an 80% chance. The table combines every possible starting quantity and rounding outcome.
Ten-pack Legendary fragment guarantee
After clearing Stage 10, a purchase of 10 Special Chests guarantees at least 5 Legendary weapon fragments in total. It does not promise 5 Legendary weapon selections. If the 60 normal selections award fewer than 5 Legendary fragments, extra fragments fill the shortfall for one randomly chosen eligible Legendary weapon. A single Special Chest has no such guarantee.
This guarantee is unavailable before clearing Stage 10.
Crew Chest
Available after clearing Stage 30. 1 chest: 200 Pearls. 10 chests: 1,800 Pearls. Each chest chooses one of the six crew members below with equal chance, then awards 2–6 matching Crew Fragments.
| Crew | Chance in 1 chest | At least once in 10 chests |
|---|---|---|
| Reefbud | 1/6 (16.666667%) | 83.849442% |
| Keenfin | 1/6 (16.666667%) | 83.849442% |
| Snapclaw | 1/6 (16.666667%) | 83.849442% |
| Tidebeat | 1/6 (16.666667%) | 83.849442% |
| Frostfrill | 1/6 (16.666667%) | 83.849442% |
| Lucky Clam | 1/6 (16.666667%) | 83.849442% |
| Quantity | Chance for any crew | Chance for one specific crew with this quantity |
|---|---|---|
| 2 | 1/5 (20%) | 1/30 (3.333333%) |
| 3 | 1/5 (20%) | 1/30 (3.333333%) |
| 4 | 1/5 (20%) | 1/30 (3.333333%) |
| 5 | 1/5 (20%) | 1/30 (3.333333%) |
| 6 | 1/5 (20%) | 1/30 (3.333333%) |
Ten Crew Chests make 10 independent openings with these same chances. Duplicate crew rewards are possible. There is no extra ten-pack reward guarantee. Stage progress beyond Stage 30, ownership, level and equipped crew do not change these chances or quantities.
About these probabilities
Percentages are rounded to six decimal places, so displayed totals may differ slightly from 100%. Each purchase uses new random selections. Past purchases do not increase the chances of future rewards.
Reward rules reviewed on October 3, 2026. Check that the version above matches your game. This page covers paid-Pearl Special Chests and Crew Chests.