What stem is "frozen tilapia"?

Answer: Frozen tilapia, an online buzzword, comes from trisomy. Weapons that can be used to commit crimes. Of course, you can eat it.

Extension:

The stem comes from the novel Three-body. The following is the original text:

Shi Qiang took out half the documents in front of him and put them back, apparently losing interest. "Yes, fish will commit crimes! I once handled a murder case where a woman cut off her husband's things. Know what to use? Frozen tilapia in the refrigerator! After the fish is frozen hard, the row of thorns on its back is like a sharp knife.

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