elements of the mineral skeleton, typically composed of silica or calcium carbonate.
Alternative form for spicule : spicules.
from Hooper and Wiedenmayer, 1994
from Rützler and Smith, 1992
from Hooper and Wiedenmayer, 1994
from Hooper and Wiedenmayer, 1994
from Hooper and Wiedenmayer, 1994
drawing F. Hiemstra
drawing F. Hiemstra