Now don't be alarmed. I won't let you be swept from my back. I am only going to wash my head. See me swim directly under this mass of sponge, swaying out from a rock. There will be no bits of sand clinging to me after I have been sponged a few moments.
Here is a sponge that looks as if almost as large as your sun when it rises out of the water, but if you squeeze that fellow dry--the sponge, not the sun--it will not begin to be the size it is now. You could press it into a bowl of moderate size when dry, but then take it to the pump or the faucet, fill it with water, and my, what a balloon!
Sponges were once called "worm-nests," and were thought to be a mere kind of seaweed. But looked at under the sea, it would be known at once that they are neither nest nor weed.
Once in awhile sponges seem to spring directly up from the mud without anything to cling to, but generally they are fastened to rocks or large stones, and spread out and out from them. Here they look so much like a kind of herb, that Folks who make a study of things in nature, and are called naturalists, for a long time took them to be a kind of sea-plant, and for years it was a puzzle as to just what they were.
All are full of pores or layers of small cells, and some are quite pretty from having a fringe about the cells like eyelashes. There are others curiously shaped, looking like coral sprays, and here and there they look like helmets; then there is another form that seems to have long fingers running out, and is called "mermaid's gloves."
The form called "Venus flower-basket," large and basket-shaped, might answer for a mermaid's work-basket, and hold her thimble, scissors, and thread. You had better take care! A mermaid may be near this very moment, and hear you laughing. And remember, she could spin you round from one end of the sea to another, then leave you high and dry on a big rock in the middle of the ocean.
Now, on what do sponges feed? Dear sakes, as if they fed on anything! Yet they do. Although they branch and bunch out in the forms described, yet they do not roam about, but only float or swim out as far as they can stretch themselves while firmly fastened to a rock. Here they take in specks or particles that float through the water; they pass through the open pores of the body, and answer for food. The water constantly passing through them serves to refresh and keep them round and healthy.