Registration numbers must be not less than three inches (3) in height and the. documented name must be in 4-inch letters. Spaces or hyphens should be equal to the. width of a letter other than I or a number other than 1. On vessels so configured that a.
Sponge Animation: Spicules. Spicules are microscopic structures of hard crystal material with fantastic shapes unique to the different species of sponge. They are part of the skeleton that helps give the sponge its shape.
sponges & cnidarian notes b1. 1  Spongin is a network of flexible, protein fibers making up the spongeâs skeleton. 2  Spicules are tiny, hard particles shaped like spikes or stars in the skeleton of some sponges. 3  Spicules are made of calcium carbonate or silica.