Identifying a few critters - can you help?

[newreefer_59]

Attached photos are not great, but hopefully good enough.

The first is of a small (1/2 inch) snail like animal in my tank and there seem to be a few of them. Are they harmless?

The second are small worm like critters in my sump. Are they ok just left there and is it a good idea to remove them and/or place some old coral within my sump?

Many thanks.