Should I be worried that there might be others? If so, what should I do?
That is almost certainly the larva of a carpet beetle, likely the Furniture Carpet Beetle (Anthrenus flavipes). They are distinctively hairy and striped.
(image from wikimedia)
Carpet beetles are found world-wide and are a pest of homes, workplaces, museums, basically anywhere that textiles, paper, or foods are contained. They will happily eat wool, silk, fur, hair, bone and shell (e.g. tortoise shell, not sea-shell).
Getting rid of them is difficult - you need to clean out any areas where they can live, this includes all your clothes (hot tumble-dry for 1 h, or keep in sealed bags for 2+ months), any natural-fiber carpets, cupboards, furniture - literally anywhere dust can accumulate. Often easiest to get a pest-control expert in to deal with them.