Q: Context: Steatoda nobilis has a brown bulbous abdomen with cream coloured markings that are often likened to the shape of a skull. The legs are reddish-orange. Females range in size from about 9.5 to 14 mm in size, while males are 7 to 11 mm. Males are able to produce stridulation sounds during courtship, by scraping 10-12 teeth on the abdomen against a file on the rear of the carapace.

Question: a spider with a skull on its back?
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The relevant information to answer the above question is: Steatoda nobilis has a brown bulbous abdomen with cream coloured markings that are often likened to the shape of a skull. So the answer is Steatoda nobilis.