Answer:
Due to presence at early days of the planet.
Explanation:
We only find the remains of single celled organisms in the oldest fossils because the single celled organisms are the organisms that were present in the early days of this planet. These single celled microbes were present about 3.7 billion years ago while on the other hand, the oldest rocks are only a little older i. e. 3.8 billion years so these single celled organisms are considered as oldest fossils on this planet.
The correct answer is: sea stars
All animals listed above are invertebrates. One of the characteristic of invertebrates are that they are protostomes with the exception of Echinodermata (sea stars). The difference between protostomes and deuterostomes is in their embryonic development (orgin of mouth and anus).
In protostomes the mouth forms first: the oral end of the animal develops from the first developmental opening. On the other hand in deuterostomes the first opening (the blastopore) becomes the anus, and the oral end of the develops from the second opening.
Humans are also deuterostomes.
Answer:
Plants have a process called photosynthesis that enables them to take carbon dioxide out of the atmosphere and combine it with water.
Explanation:
