There have been recent reports
Thousands of "sand coins" in the United States were washed up on the beach to die,
It has aroused heated discussion among netizens.
What is sand coins,
Is it a Saudi Arabian coin?
In fact, "sand coin" is an animal.
What kind of animal is that?
What kind of animal is SandCoin?
Sand coin is actually an aquatic wildlife in the sea, a kind of echinoderm, belonging to the sea urchin class.
The sea urchin is round, spherical or heart-shaped, with warts and long, movable spines, while the sand coin is flattened and has short spines that look like animal hair and inconspicuous forked spines.
The official name of the sand coin is the cake sea urchin. However, sand coins have many other names, which are coin-shaped and have thin edges, called sand coins or sand coins. The yellow or purple cracked-edged sea urchins that grow off the coast of East Africa appear larger and thinner among their cohorts.
The reason why the pie sea urchin is called a sand coin is probably because the upper and lower sides of its carapace are obvious, and there are 5 petal-shaped areas on it, which is very similar to the shape of a coin.
However, when the sand coins really look like coins, it is not when the sand coins are alive, the living sand coins are light brown and purple.
Most of what we see is what they look like after they die, and the white, round things are their bones, with patterned shapes on them, which do look like silver coins.
Generally, sand coins can only survive for a few minutes after leaving the sea, and when the tide recedes, they begin to dry out and die.
Can you see sand coins in our country?
Sand coins are widely distributed, and they can be found in shallow seas, intertidal zones or subtidal beaches around the world, some hidden in sand, and some on the seabed at a depth of 3,000 meters, so that we usually can't see them.
Sand coins, like other sea urchins, are naturally timid and will flee as soon as they see an enemy, because they cannot move quickly, and burrowing into the sand is the best choice.
When they burrow in the sand, the organic particles and plankton that flow into their mouths with the water are their food.
The sand coin is on top of one side of the petal pattern, while the side with many synapses is on the bottom. There are holes on both sides, and the division of labor is clear, and the tube foot protruding from the upper face is used for breathing, while the tube foot protruding from below is used for feeding, or for movement with the thorn. The spines at the bottom first prop up the body, and then the tube foot grasps the rock and moves.
Image source network
Sand coins do not have a mammal-like mouth, only a more primitive mouthpiece, located in the center below. The five tooth-like things inside the mouthparts are used to grind food.
Can sand coins be eaten?
Sand coins produce very little edible meat, even less than other sea urchins and starfish. Although it was not found to be poisonous, its meat was not tasty.
Editor: Xi Yuxuan
Source: Popular Science China