graptolite

As an adjective aquatic

is relating to water; living in or near water, taking place in water.

As a noun graptolite is

any of a group of extinct aquatic colonial invertebrates, of the class graptolithina , from the cambrian and carboniferous periods.

As an adjective extinct

is extinguished, no longer alight (of fire, candles etc..

As a noun graptolite is

any of a group of extinct aquatic colonial invertebrates, of the class Graptolithina, from the Cambrian and Carboniferous periods.

As nouns the difference between graptolite and sicula

is that graptolite is any of a group of extinct aquatic colonial invertebrates, of the class Graptolithina, from the Cambrian and Carboniferous periods while sicula is the hard, triangular apex of a graptolite from which it grows.