There might be other ways to obtain this item, but it might not be ever available again.
The Crab Armor is an event item you could've bought with Tickets during the Release Event. It bares a striking resemblance to King Crab, the boss of the Release Event. It overall looks pretty buffed, with the spiked shoulder pads and chest armor that resembles a 6-pack.
After frying up the crab meat from King Crab, the survivors finally had some down time to assess the damage done to the beach. Needless to say, the collateral was very high. Besides the landscape being utterly destroyed, it was apparent that something needed to be done with all the smaller, normal dead crabs on the beach.
It's a good thing that glue exists.
- This helps reduce Ticker radiation by a small amount, but don't go blowing up their tanks!