Random influx of guests?

Why was there a random big amount of guests earlier today? I don't mean 5, or 6, I mean 17-27. Seriously.

See attachments, cause no one else was online to witness it.

it happens. sometimes someone posted a link to here and then a bunch of guests come over. although that's usually that most of them then look at the same page.
also, I think some search engine spiders are listed as guests.
anyways, nothing actually major. there've been even more guests at the same time in the past, and usually nothing bad happens as a result.

These are search-engine spiders that are unknown to the system. Since they rapidly access many topics at the same time, one spider can easily be seen as 20 guests. This is a problem with SMF that cannot be fixed easily.

There is support for the majority of spiders, but adding all of them is nearly impossible.

Since they rapidly access many topics at the same time, one spider can easily be seen as 20 guests.

Which would explain why most of them view different topics, and why a lot are at the same time.