These look like eggs of some sort. Have you ever seen them before or know what they are – possible slug????
Thank you for contacting the Toronto Master Gardeners. Yes I think this could be slug eggs. Slugs are attracted to a dark, cool and damp environment, and they will come indoors, especially in an older home that is more likely to have a damp basement and lots of cracks and crevices for them to enter, Their presence could be a sign of a water leak. They also have a good sense of smell and are attracted to pet food in particular. They are unlikely to cause damage indoors, except perhaps to some indoor plants. Most slugs lay their eggs in the fall, which then overwinter and hatch in the spring. The eggs can be destroyed by dropping them in a bucket of soapy water.
Managing slugs in the garden may help to keep them out of the house. Here is some information in a previous response from the Toronto Master Gardeners about controlling slugs :
https://www.torontomastergardeners.ca/askagardener/slug-and-snail-control/
Best of luck with your slugs !