I recently sampled an interesting fresh Japanese sea cucumber appetizer at Sushi Yasuda. It's from the special appetizer menu that is printed on a thin yellow sheet. Small sea cucumber from Japan is sliced to reveal cross-sections.
Very crunchy, like dense fresh abalone. A texture play more than a display of its intrinsic taste, although the surrounding seaweed did augment the ocean sensations. Probably not for most diners, but I enjoyed it.