Dododex
ARK: Survival Evolved & Ascended Companion
Utility Tips

What is a trilobite used for? trilobite battling strategies in ARK: Survival Ascended & Evolved.
Best way to farm chitin from these guys: use a moschops. The moschops can collect around 200 chitin for one trilobite where as using an axe will give you around 80. Only downside, moschops can't get pearls or black pearls from them, so you'll have to collect those another way.
I like them for Chitin, so I can have more cementing paste. To make some cementing paste, you can use the Stone and Chitin, or you can put Keratin in in place of the Chitin. Keratin is a lot harder to get, you need stegosaurs for them. Chitin can come off of Trilobites and flying ants.
If you spawn in The Footpaw (selecting West Zone 2, or sometimes South Zone 1 in The Island map) you can easily find them in early game. Just look for the narrow peninsula in the East (a very safe place with almost no predators, literally none in the South area). You will frequently find trilobites on the southwestern coast.
Trilobites are very usefull, because they're passive and weak: that makes them probably the easiest source of chitin, a convenient source of meat and a source of oil and silica pearls, two important resources you'll need late in the game.