Range Minimu Query: Given an array A[1,n] of n ordered objects (such as numbers), a Range Minimum Query (or RMQ) from i to j asks for the position of a minimum element in the sub-array A[i,j]. RMQs can be used to solve the lowest common ancestor problem.
The reasons that we do not eat or recommend shellfish are very similar. Shellfish are bottom feeders and feed on parasites and dead skin, many times from dead animals. They do not have appropriate digestive and filter systems to purify toxins and parasites from their body and flesh.
Can Pregnant Women Eat Crawfish. Sure. The only reason why shellfish is sometimes frowned upon is if it's not properly cooked. I've eaten (and cooked) a ton of crawfish myself, and I can tell you I boiled the you-know-what outta those suckers. I think it should be fine. The danger from undercooked shellfish is listeria, but especially in LA where the crawfish are fresh, I don't think you have to worry.