Well there are many catastrophic scenarios that we already overcome. You should consider educating yourself about the great filter. A great filter is a hypothetical barrier that each civilization can or cannot overcome. From here on things get a little complex so I won't bore you with them. But there are experts in this theory called great filter and I'm sure they can tell you a lot about.
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Yes it is because sedimentary rock is lots of rocks condensed into 1
The answer is:
Echinodermata
The word echinodermata is Greek which literally means "Spiny Skin". Echinodermata is a phylum under kingdom animalia. Not all of them have spiny skins, but most of them do. Other characteristics would be their radially symmetric body. They have appendages that grow outward from the center. Examples of echinoderms would be sea stars and sea urchins.