spicule
noun
spic·ule ˈspi-(ˌ)kyül 
1
: a slender pointed usually hard body
especially : one of the minute calcareous or siliceous bodies that support the tissue of various invertebrates (such as sponges)
2
: a spikelike short-lived prominence appearing close to the chromosphere of the solar atmosphere
spicular
ˈspi-kyə-lər
adjective spiculation
ˌspi-kyə-ˈlā-shən
noun 
Example Sentences
Recent Examples on the Web According to a press release, the team observed the emergence of spicules while also monitoring nearby magnetic fields. 
Jason Daley, Smithsonian, 15 Nov. 2019 According to this new research, the same process could create the much smaller spicules. Jason Daley, Smithsonian, 15 Nov. 2019 In fact, researchers at his lab released a major model of how the spicules form in 2017. Jason Daley, Smithsonian, 15 Nov. 2019 The spicules surge thousands of miles high, passing through the chromosphere and into the sun’s corona before collapsing. Nicholas St. Fleur, New York Times, 23 June 2017
Jason Daley, Smithsonian, 15 Nov. 2019 According to this new research, the same process could create the much smaller spicules. Jason Daley, Smithsonian, 15 Nov. 2019 In fact, researchers at his lab released a major model of how the spicules form in 2017. Jason Daley, Smithsonian, 15 Nov. 2019 The spicules surge thousands of miles high, passing through the chromosphere and into the sun’s corona before collapsing. Nicholas St. Fleur, New York Times, 23 June 2017 Word History
Etymology
New Latin spicula & Latin spiculum; New Latin spicula, alteration of Latin spiculum head of a spear or arrow, diminutive of spicum, spica ear of grain
First Known Use
1785, in the meaning defined at sense 1
Medical Definition
spicule
noun
spic·ule ˈspik-(ˌ)yü(ə)l
: a minute slender pointed usually hard body (as of bone)