Roach nymph.

Most insects go through metamorphosis -- a change in physical appearance, physiology, and anatomy -- from hatchling to adulthood called "instars". We are most familiar with Lepidopterans (moths & butterflies) because of the cocoon or chrysalis. Most don't require that particular manifestation of change -- most simply change gradually over several episodes of shedding, activity, and quiescence. Like the roach. Yours is a youngster. Ick.

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