Lactoria cornuta

Actinopterygii: The Actinopterygii, or ray-finned fishes, constitute a class or subclass of the bony fishes. The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines ("rays"), as opposed to the fleshy, lobed fins that characterize the class Sarcopterygii. In terms of numbers, actinopterygians are the dominant class of vertebrates, comprising nearly 99% of the over 30,000 species of fish. (Wikipedia)

Brackish: Brackish water or briny water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. (Wikipedia)

Tropical: The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at 23° 26' 16" (or 23.4378°) N and the Tropic of Capricorn in the southern hemisphere at 23° 26' 16" (or 23.4378°) S; these latitudes correspond to the axial tilt of the Earth. (Wikipedia)

Curved: The overall shape of the ichthyolith curves in one direction.

Long: The ichthyolith is at least three times longer than it is wide.

Cavity: The ichthyolith has a central nerve cavity. This is a base keyword included whenever an ichthyolith has a cavity, even when the cavity is further categorized with an additional keyword.

Cavity Wide: The ichthyolith's cavity is distinctively wide (defined as more than four times as wide as the "walls" surrounding it at its midpoint; alternately phrased, the cavity takes up more than than two-thirds of the total width of the cross-section at its midpoint).

Triangular: The base of the ichthyolith is the widest part.