spicule

As a noun spicule

is a sharp, needle-like piece.

As an adjective tetraxile is

having four branches diverging at right angles; said of certain spicules of sponges.

As nouns the difference between spicule and amphidisc

is that spicule is a sharp, needle-like piece while amphidisc is (zoology) a small siliceous spicule having a denticulate wheel at each end, found in freshwater sponges.

As nouns the difference between spicule and clavula

is that spicule is a sharp, needle-like piece while clavula is a ciliated bristle of some sea urchins.

As a noun spicule

is a sharp, needle-like piece.

As an adjective spicular is

of, pertaining to, or formed from spicules.

In astronomy|lang=en terms the difference between spicule and macrospicule

is that spicule is (astronomy) a jet of matter ejected from the photosphere of the sun while macrospicule is (astronomy) a very large-scale spicule.

As nouns the difference between spicule and macrospicule

is that spicule is a sharp, needle-like piece while macrospicule is (astronomy) a very large-scale spicule.

As nouns the difference between spicule and calcarean

is that spicule is a sharp, needle-like piece while calcarean is (zoology) any sponge, of the class calcarea , that has a skeleton composed of calcium carbonate spicules.