Some spicules are formed of the mineralized substances calcium carbonate and silica, while others are made of an organic substance called spongin. Sponginskeletons<span> were and are used as scrubbers in bathtubs, though they are fairly expensive. The ubiquitous bathtub accessory called a lufa is NOT a </span>sponge<span>, but a plant.</span>
Explanation:
Larger lenses are heavier, and tend to sag under their own weight, ruining the image quality as the lenses distort. The long mounting tubes are hard to make mechanically stiff, and so they tend to flex under the weight of the lens, making it hard to keep the optics in alignment.
Answer:
d
Explanation:
because i said so lol - trust you will not be sorry
3 hours because it dangerous
