Rivet eggs are hard; their outer shell is mainly silicon and resembles a microchip similar to what you might find inside of a computer. Rivet eggs, like microchips, are excellent conductors of electricity and can withstand higher average temperatures.
In fact, if lightly charged, Rivets will hatch quicker and be healthier as adult creatures.
Rivets are the Science and Research Center's basic attempt at integrating organic material with computer chips. Rivets are able to perform basic calculations with numbers (like addition and subtraction) but they aren't able to archive data, organize it, and perform complex queries.
Ark citizens have inquired to the Science and Research Center, wondering how Rivet firmware operates and how it could be potentially upgraded. The Science and Research Center has issued no public response. This has spawned an underground community of "Rivet hackers" who try to modify and upgrade their creatures' firmware and programming. In response, the Town Hall has vaguely issued a statement that says, "Tampering with genetically modified creatures may be dangerous. It is not recommended." No legal actions have been taken against the hacker community.