Why are species like the lionfish considered "invasive"?

According to the big bang theory, after the "bang," the universe remained dark until about  300,000 yearsone billion yearsthree minutesthree billion years  later, when neutral atoms began to form.

Which nucleotide component contains nitrogen

Which of the following is one way in which organisms such as clown fish and sea turtles are able to overcome the many dangers that their offspring encounter and ensure that their species population numbers stay relatively steady