spicule

n. small needlelike part or structure

This article is about the skeletal structure. See also Spicule (solar physics). Spicules are skeletal structures that occur in most sponges. They provide structural support, as well as deterrence against predators. Large spicules, visible to the naked eye are referred to as megascleres, while smaller, microscopic ones are termed microscleres. Spicules have four major symmetry types: Monaxon (simple cylinders with pointed ends), triaxon, tetraxon, and polyaxon. Sponges can be calcareous, siliceous, or composed of spongin. The meshing of numerous spicules serves as the sponge’s skeleton. The composition, size, and shape of spicules is one of the largest determining factors in sponge taxonomy.
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Noun
1. small pointed structure serving as a skeletal element in various marine and freshwater invertebrates e.g. sponges and corals
(synonym) spiculum
(hypernym) process, outgrowth, appendage

(n.)
Same as Spicula.
  

(n.)
Any small calcareous or siliceous body found in the tissues of various invertebrate animals, especially in sponges and in most Alcyonaria.
  

(n.)
A minute, slender granule, or point.
  

Synonyms and related words:
bramble, brier, bristle, burr, cactus, catchweed, cleavers, goose grass, needle, nettle, pine needle, prickle, quill, spiculum, spike, spikelet, spine, sticker, thistle, thorn, yucca