Opportunistic feeders, their diet varies from one region to another. In the Antarctic, killer whales eat about 67% fishes, 27% marine mammals, and 6% squids. Killer whales in the Bering Sea (near Alaska) eat about 65% fishes, 20% squids, and 15% marine mammals.
Even though your shower grout looks dry, using it too early or sealing it before it's ready may damage it, leading to premature failure. Most cement-based grouts require a cure time of 48 to 72 hours before applying a penetrating sealer.
There's a difference between dried and fully cured. I've grouted tile within 24 hours of laying it, but that was under ideal conditions. I'd recommend waiting at least 24 hours. Same with grout. Just note that it takes a lot longer than 24 hours for grout to cure, before you should apply sealer.