A: The confusion can be cleared up by
reading "+" where "=" appears, so that
the names of the items are "Dagger +1/+2
vs. Dolphins" and <"Trident +1/+3 vs.
Elemental Beings.">

Undersea magic items
by Roger E. Moore

Dagger +1/+3 vs. Koalinth
These are frequently found in the possession of Tritons,
which are typically armed with a dagger and one other weapon.
It is a coral or fish-tooth dagger, usually with a carved handle.
If an alignment is present in such an item, it will be Good.
XP value: 100
GP value: 1,000

Spear +2/+4 vs. Sharks
Also known as a "Sharkbane" spear, this is a large lance with a
point made from a shark's tooth. These items, originally
enchanted by Triton mages or clerics, are greatly sought after by
Mermen and Sea Elves, who will readily TRADE valuables to
acquire one.
XP: 1,500
GP: 10,000

Trident +1/+3 vs. Reptiles
This weapon is especially effective against Dragon Turtles,
Lizardmen, dinosaurs, crocodiles, and other types of aquatic
and non-aquatic reptiles.
XP: 1,000
GP: 10,000

Trident +1/+3 vs. Lacedons
Another magical weapon frequently found in the possession
of a Triton or in a Triton lair. All tridents of this sort have a
NG alignment and are most effective when used against the marine variety of the ghoul.
Experience Point value:
1,000.
Gold Piece value: 10,000

Necklace of Air Breathing
Useless or dangerous to most types of creatures, this device
is sometimes seen employed by Locathah and other creatures
of the deep who cannot normally breathe air. Creatures which
normally breathe air will, upon donning the necklace, find their
lungs immediately filling up with water. If a save vs. magic is not
made, the victim will fight at -1 to hit in the first round following
the donning of the necklace, and at an additional -1 to hit in each
round thereafter, to a maximum penalty of -4 in the fourth round.
After four rounds, the victim will become unconscious and will
die of drowning two rounds later unless preventive measures
are applied to the victim. There is an 80% chance of saving the
victim’s life. If the victim is unconscious before the necklace is
removed, the chance for survival (after lifesaving measures are
taken) drops to 50%. Experience Point value: Nil (to airbreathers).
Gold Piece value (to air-breathers): 500.

Dagger +1/+2 vs. Dolphins
Creatures most severely affected by this weapon include all
those known or thought to be native to the elemental plane of
water, such as Tritons, Water Weirds and Water Elementals.
Another of the items crafted by Sahuagin clerics, this trident is
normally only found in the possession of the most powerful
members of that society. Experience Point value: 800. Gold
Piece value: 10,000.

Periapt of Protection from Vampiric lxitxachitl
Made by Triton clerics in many shapes and colors, this item
acts as a permanent ward against the vampiric lxitxachitl as well
as Lacedons. Neither of those types of creatures can voluntarily
get closer than 10 feet away from the wearer. If forced inside this
10-foot radius, the creature will fight at -2 to hit. Experience
Point value: 1,500. Gold Piece value: 15,000.

Spongestone
by Bruce Humphrey

In its “dry” state, a Spongestone appears as a chunk of stone
which is rigid, quite porous, and relatively light in weight compared
to an ordinary piece of stone.

This substance has the ability to soak up water from any solid
or liquid substance it is placed in contact with. Each Spongestone
can absorb a volume of water equal to 30 times the volume
of the stone itself; i.e., a Spongestone with a volume of I cubic
foot will soak up 30 cubic feet of water before becoming saturated.
A dry stone will automatically soak up its capacity in water in
the space of three rounds, assuming that a sufficiently large
source of water is at hand. When dry, a Spongestone is light
brown in color. When it is filled with water to one-third of its
capacity, it becomes a darker brown. At two thirds of capacity,
the stone turns light blue, and when it is filled to the maximum,
the stone assumes a deep blue color. (This property makes a
Spongestone quite conspicuous in certain circumstances, such
as when it is found on the bottom of a body of water.) A Spongestone
is not “softened” by the absorption of water, such as an
actual sponge would be; it retains its rigidity no matter how
much water it contains.

Any Spongestone which is saturated to capacity can be
forced to release its stored-up water by the utterance of a command
word. Water which is released in such a manner will drain
out of the stone twice as fast as it was absorbed, so that 1½
rounds after being commanded, a Spongestone will be dry and
the water it contained will have drained into a receptacle or onto
the ground. A stone which has just released all its water will not
be able to begin absorbing water again for one round; at the end
of that time, the stone will begin to re-absorb the water it had just
released, if it has not yet been removed from the water.
A Spongestone which has absorbed water up to its capacity
can be transported without danger to the bearer. However, a dry
or partially filled stone will draw water from the body of a character
or creature who touches it without the benefit of clothing or
armor or some other protection which acts as a barrier to absorption.
Anyone who comes into contact with the stone against
an unprotected body part will take 5-10 (d6+4) points of damage
per round due to dehydration, risking unconsciousness and
death if the contact with the stone is not broken in time.
A Spongestone will absorb pure water, filtering out all impurities
and pollutants, so that the water which is released is
equally pure and may be safely consumed.

A Spongestone of relatively large size may be cleaved in half
by a blow from any magical edged weapon, as long as the
original stone was at least one-half cubic foot in volume. However,
each time such a cutting is attempted, there is a 50%
chance that one of the resulting halves will lose its magical
properties, a 25% chance that both halves will be rendered
useless, and a 25% chance that both halves will be unaffected.
Experience Point value (for one cubic foot): 2,000.
Gold Piece value (for one cubic foot): 15,000.