Art experts think they have uncovered one of the first ever portraits of a pet guinea pig.
A 16th century oil painting showing the animal being cradled between three children will go on show at a new exhibition later this year.
The portrait, believed to have been painted around 1580 by an unknown artist, shows three young children holding the animal which had recently been introduced into Europe from South America by Spanish merchants.
It will form part of an exhibition, called Elizabeth I And Her People, which opens at the National Portrait Gallery in central London in October.
A gallery spokesman said: "We know that guinea pigs were introduced into Europe by traders and were kept as exotic pets.
"While archaeological finds for domestic guinea pigs in Europe are rare, a partial skeleton of one that dates from around 1575 was discovered at Hill Hall in Essex, an Elizabethan manor house."
The youngest child in the painting is also holding a small bird, possibly a goldfinch, which was often used to symbolise Christianity in works of the period.
The exhibition includes jewellery, costumes and coins from the period as well as paintings.