Money spider
From Tardis Wiki, the free Doctor Who reference
A money spider was a breed of spider on Earth.
In the 1890s, a money spider grown to enormous proportions by a zygma beam was discovered by the Fourth Doctor in the basement of the Palace Theatre. Henry Gordon Jago advised the Doctor not to kill it (TV: The Talons of Weng-Chiang) saying "it’ll bring us luck." (PROSE: Doctor Who and the Talons of Weng-Chiang)