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.
The term speleology is also sometimes applied to the recreational activity of exploring caves, but this is more properly known as caving, potholing, or (not usually by participants) by the largely obsolete American term, spelunking.